Probably sounds a bit silly and is very easy but how do you remove the rear speaker 6x9 covers on a 92 z28 I dont want to damage them!

 

Remove one screw in coat hanger and remove screw and hanger. Cover(sail panel) slides straight up and then simply lift off. Sail panel has 4 hooks that fit into slots on interior. Badman

 

^^^

Exactly, they are very simple to remove

 

Sorry forgot to mention that it is a convertible.

 

Just in case you still haven't resolved this, I'll take a stab.
I'd imagine that 92 Firebirds and Camaros are the same. The only way I've found to get to the speakers is from the back by taking off whole panel.

If I remember right remove the black plastic pieces where the where the seat belt goes into the body, and the plastic trim on the edge of the panel. There are several screws around the outside of the panel. I believe that you have to put the rear seat down to get to one or 2 of them. After all the screws are off, the panel lifts off. Disconnect the speaker and interior light harness and then remove the speaker.

Enjoy.

btw, the speakers in the convertible are not 6x9s. They're either 5 1/4 or 6 1/2.