Can you change clutch plate without removing the engine?

You need the right equipment and knowledge to do this job there are a lot of cables wires etc that need to be removed before the gearbox can be loosened and removed.
There are also a lot of special tools required and the job is best done on a ramp or pit to gain access.
Trying to do this on the ground would be difficult and very dangerous also the engine needs to be suspended when the gearbox mounts are removed.
It is impossible to remove the clutch pressure plate, plate and hydraulic bearing on the C4 without removing the gearbox.
Take it to a garage/ clutch specialist.

jack up engine loosen trans from engine pull trans back to access the clutch assembly remove fly wheel remove clutch pressure plate and replace reassemble be careful

clutch is provided in the car for the smooth gear shifting without use of it the clutch plates,pressure plate and the flywheel damage due to which there will b the power lose of engine

It is best to replace the clutch driven plate, pressure plate and release bearing at the same time.
You have to remove either the transmission or the engine(or both). On some vehicles it is not possible to remove the engine without the transmission. I prefer removing the transmission only, since it does not require a hoist. (Removing engine and transmission complete is a bit more complicated,theres much more things to disconnect, but makes things easier when mating the transmission to the engine after replacing the clutch assembly). When removing the transmission only make sure the engine is properly supported, since the engine is supported by the transmission and vise versa.
Take note of all pipes and cables that you remove and mark them with masking tape since that gives you something to write a description on. Remember to mark the spot that you disconnect from as well. Taking close-up pictures of the engine bay will work wonders when your memory fails.
Read through this : http://www.fixya.com/cars/t4984410-remove_front_axle_get_engine (solution 2)
Drain transmission oil. Remove the driveshafts as described. Remove any electrical connections to the gearbox.
Remove the gearshift linkage. Remove the clutch cable/clutch operating mechanism(hydraulic clutch) Remember to support the engine before unbolting the transmission from the engine. Remove any mountings still connecting the transmission to the body of the car..
Remove the transmission from the engine bay. It is possible to do this by hand (a helper would be a plus at this point)
The clutch pressure plate is then visible on the engine and held in place by 6 bolts. It can be removed along with the clutch plate(which will drop free once the pressure plate is removed. Replacing the clutch is pretty straightforward, except that the clutch plate needs to be centered, or the transmission wont go back on. Autozone stocks a clutch centering tool which you can purchase although some clutch kits come with the centering tool supplied, else you can fashion one out of a wooden dowel. The dowel needs to fit snugly into the recess in the centre of the flywheel. Use insulation tape to build it up if it is too thin. The clutch plate can go in one way only. You will note that the clutch plate centre has a metal plate fitted on one side. This is the transmission side of the plate. Fit the clutch plate and pressure plate to the flywheel and tighten the bolts just enough to hold the clutch plate in place so that it doesnt move around. Using your centering tool make sure the clutch plate is nicely centered. Then tighten the bolts to the specified torque. Which means tighten them up without breaking them. Get the transmission fitted to the engine. This may take some doing especially if the clutch centering didnt go too well. Now reconnect everything and drive the vehicle to the nearest alignment centre to re-set the wheel alignment.

The clutch can be done by unbolting the transmission from the engine after removing the drive shafts, support mounts and linkages and then sliding the transmission to the side resting between the subframe and inner guard. There is not a great deal of room to work with but the job can be done without removing the engine.

You need to get a manual. Try the Haynes manual for your car. Try autozone; generally available for around $20. This is not the type of thing that can be covered here in enought detail to do you any good.
Basics are;
disconect the negative battery cable, set parking brake
locate the trans mounting bolts
get something to support the engine and something to support the trans
seperate the trans from the motor by removing the bolts. On transverse mounted engines you will probably have to pull the trans to get enough room to remove the clutch and you'll probably have to remove the 1/2 shaft axles (front wheel cars) or drive shaft (rear wheel drive cars)
If replacing the entire clutc assembly (pressure plate, flywheel, and clutch), loosen the pressure plate mounting bolts gradually working your way around the pressure plate. If only replacing the clutch then seperate the sperate the pressure plate from the flywheel and remobe. Align clutch with a clutch allignment tools and replace pressure plate. Torque bolts to spec. reconnect the trans to the motor. Few other things to think about. You should replace the throwout bearng when doing a clutch. Lube the clutch fork as directed without getting lub on the clutch face. Hopefully I have convinced yu to get a manual or you will be hating life if you take this on without it.

Easily. Remove the gear box, the roller bearing is fitted to the box, so yoou dont have to worry. The clutch and plate is fixed to the engine held in with hex nuts, you'll need allan keys to remove them, remove the bolts and the clutch and pressure plate will fall away. Take the new one from the box, being carefull not to contaminate with grease or oil that is on your hands, fit the pressure plate into the clutch assembly and line up to the engine and loosly tighten up so the pressure plate will move with a little resistance. This is where the fun starts. Get your socket set handle and push it through the housing into the engine. Centralise the pressure plate as accurately as you can. Offer the gearbox slowly to the clutch and try to push it home. The pressureplate should have enought movement in it to move slightly to allow the gear box to fit. Once fitted, slowly and levelly remove the box, then tighten all of the clutch housing into place. Refit the box, tighten and go for a cup of coffee to congratulate yourself! The only other adjustments you have to make are to the clutch cable. Loosen the lock nut, loosen the adjuster bolt, tighten the adjuster bolt until the cable becomes taught, depress the clutch and you should feel the clutch release. Tighten the locknot and that's it. Hope all goes well, any problems let me know any problems let me know and I'll help. Regards, Dave.

undo centre wheel hub nut 30mm/32mm, socket. undo lower wish-bone outer bolts, disconect battery,/remove starter motor,/remove transmission mounting bolts to body frame ,/ remove all surrounding bolts around bell housing transmission,/ remove clutch cable from transmission,/ remove drive shafts from centre hub and transmission,/ make sure car is standing on axle stands at front of jacking points,/use a trolley jack to suport engine sump with a piece of wood,/ slide transmission away from flywheel,/lower transmision on floor,/undo all clutch plate preasure bolts 10mm,/remove thrust bearing located on centre transmision shaft ,.also make sure if fitted speedo cable needs to be removed.new clutch plate should indicate flywheel ,without fitting clutch plate wrong way round/otherwise transmision will not bolt to engine block.,

You need to empty the engine from all fluids, tehn remove air filter and other parts, mount your Golf on a bridge and remove the clutch pressure plate assembly mounted on a side of the engine.

You will need special tools to align and mount the new pressure plate, and you will need to follow a procedure to reinstall the clutch without removing the transaxle.

Replacing the clutch is not an easy task for a beginner, if you do it yourself, get the haynes manual with the complete illustrated procedure.

After replacing you will have to adjust the clutch. See CLUTCH REPLACEMENT PROCEDURES.

I assume you are talking about the clutch to the transmission. They make a tool that will support the engine and allow you to remove the gearbox on most cars without removing the engine. It is a tight fit but much less work.