I have a 1996 lance camper with a 2500 onan generater lp cant get the spark plug out can you help

White Brown green and yellow are normally The 12 volt vehicle lighting colors, not 110 volt power. Generators do not have FIVE wires for the power wires out of your generator. Is this the remote control circuit? If so, I dont have a clue!

Check the fuel. If old, drain & refill it.
Check for spark.
If the fuel is there and good, trace it to the carburetor. Check the carburetor bowl for fuel.
Check the spark plug, the magneto, any switch that breaks the circuit or kills the circuit for spark.
If you're getting good fuel to the carburetor and you're getting good spark, try to start it with ether spray.
You might also want to check compression while you're checking everything else.

Is the generator coming up to proper speed? A cycles (hertz) (should be 60 in USA) meter will tell.
If it is up to speed, see if a UPS unit is made powerful enough to power the microwave. That will handle the initial starting load from the microwave.
UPS units are handy to power stuff while you are getting the gen going.

Unit is over fueling, did you change fuel pump for non OEM part? fuel carb needle maybe stuck with gum

I would not adjust it, I would say the unit has sat and carb is gummed up. Flush with sea foam and run for as long as you can under heavy load

Contact your local retailer/service center directly or online here: Contact Lance Camper

Have the demand regulator checked, and LP pressure

That knob should be to bring pressure up and down with 0 being off or the lowest range of the regulator. This regulator is adjustable for different applications apparently.

Gov and or carb out of adjustment, bad LP regulator