When I fitted Led festoon bulbs to mine.

You should find that the actual light fitting is not held into the roof lining too tightly, so gripping the longer sides of the fitting and pulling downwards, it should come out.
 
gentle tug then alls well just replaced all mine ie sunvisor footwell interior and boot lights with led much better :)
 
Yeah ive also dont the visor' boot' glovebox and footwell big difference
Glad you sorted them, yes it's quite a noticeable difference having the complete Led interior bulbs, any thoughts yet on what's your next project ?