On recent production cabs, you have to take the back of the cab. Then unscrew 6 or so screws from the inside of the front baffle. Once you do this you can remove grill cloth frame. Please don't take a knife to your grillcloth.
Really, though. I see no reason to do this. Mesa grillcloth is plenty easy to see through for mic placement and really does not affect the sound much if at all. Plus you lose the protection to the speakers.
yes you can remove it on recent production cabs (personally i keep em), but dont forget if you do; screw them back tightly and properly or else you gonna start wonderin what happened to your tone!
Ok, mine wasn't screwed but used valcro like Jeff said. It wasn't excatly easy to remove it though. There must have been some glue on there aswell. But after a few minutes I got it off.
Damn, Mesa is well crafted!
I once took the grill from the cab, it was screwed from the inside.
I decided to put the grill back on because of possible hazard of ripping a speaker with a mic (almost happened to me) and because the grill gives a good reference of distance from the mic to the speaker.
And to be honest didn't find any big difference in sound between grill on and off.