Unless your version (Canadian) is different from ours that small panel does come off fairly easily for access to the wiper motor. Have taken mine off several times as the washer pipe used to keep falling off. Don't think removing it would help much unless your numberplate is actually nut & bolted through the rear hatch door. Seem to remember there was not a lot of room down the back of the inner panel to work in.
Our number plate screws are just self tappers (4 in my case but some dealers use only 2) through the number plate and into the recess in the outside of the rear hatch door.
Some dealers use fairly thick double sided tape to hold the numbers plates on but sometimes they drop off.
DOH 
apologies here
I have completely misread the thread heading and have been rambling on about removing number plates & not number plate bulbs.
"I must engage brain before getting into typing gear"
It is a good job Derek is awake
