Like so many here I stripped the aluminum cover when I tried to do my first valve adjustment. I saw where someone suggested using a chisel to break it loose and I tried that. It cuts into the cover easily but I couldn't get enough grip to get the damn thing off by pounding on ti. Try this. Once you get some chiseled away with a chisel pound a carpenters nail set tool in to the fitting. That will dig in deep enough to get a good grab on the piece. Then you can just tap it out with the nail set tool, worked great! The hole to the right is the nail set hole. All the other mess is from the chisel.
Now, after the bike cools down over night I can check the valves easily. I used anti seize on the new fitting BTW. It had better work!