How to remove ignition barrel on renault master

First examine the key for damage. This could also be the steering lock working. Try turning the steering wheel as you turn the key. Some Renaults do have issues with keys so it might get to a point where you will need to replace the ignition barrel and the key. Unfortunately it's not cheap!

call in a locksmith as they may have a master key to allow the barrel to be turned to the point that the lock device can be moved to allow the barrel out
call on a phone and ask around

Undo the plastic casing around the ignition.
Its only around 4 screws easy.
look around the barrel where you insert the key, there should be a black plastic ring around 3 inches down the barrel this is the key reader its not fixed so twist gently and slide up the barrel as close to the key as the wires attached will allow.
then try starting, if it works then the transmitter in the key is most likely deteriorated . if it works its only a quick fix and could deteriorate in time.
a new key and coded from Renault is £300 with no guarantee that its not a different fault so look at buying one of ebay and get that paired to the immobiliser.
there is another way of bypassing the immobiliser by removing a ball bearing in the fuel pump a bit more complex.

the barrel is the bit that the key fits in
it is held in the switch body by a clip or spring
talk with a locksmith as to how the barrel comes out
your problem here is that when replacing the barrel , the key in use will not activate the immobilizer
better to have the locksmith change the barrel so that the existing key can be used eliminating the immobilizer problem

Most likely something not correct with new switch.

Worn key or barrel tumblers get a new key cut

Try the spare key.Lubricate the ignition barrel.Failing that, replace the ignition barrel and keys.

Remove the plastic cowling and the immobiliser ring,disconnect the wiring plug from the switch and then turn the ignition to position 1.There will be a pin that you push in and this releases the complete ignition barrel/steering lock/wiring assembly,the new replacement will slide in using the same technique.You can put the replacement key blade into your original fob and all will be well.

tight you replaced the lock barrell so you have new keys ,now inside this key is a chip so remove the chip from the old ley and tape it to teh transponder ,now make sure the chip that was inside the key is removed by whatever means you have to use even drilling it out.Then it will start as what happens is the new lock has the key programmed to a code for instalisation in a new vehicle and the chip in the key is confusing the transponder its a renault remember and they do have a mind of their own in regards to the immobilisor ,if you do as i say it should start if it doesnt then lock and unlock the drivers door three times slowly then jump in quick and start car within 20 secs of the key turning procedure and if that doesnt work then call the dealer and pay through the nose

most common cause is your key fob is broken.

check this by 1st gettin a camra phone goin onto the camra point key at camra and press button if you see a red light flash it is workin if not it is faulty which means a replacment key hope this helps