Thanks for all the advice everyone. Various replies:
If I can't be trusted to measure the height of my cab space vs. the height of the TV then I don't think I can be trusted to take the case off.

Seriously, it's good to know my limitations I think.
I don't know what a rotozip is. I figure it's a power tool, probably operated with one hand if it'll fit in that space, and held over my head in an awkward position means a good chance of kickback or slippage resulting in damage to the cab or to me. Sounds worrisome.
Chisel like hammer and chisel? Would that get rid of wood first or dislodge the glue and screws first?
Still, chisel might work. Little handsaw might work, too. My girlfriend suggested whatever it is people use to whittle but that could take forever.