Im trying to get a chartacter to enter a doorway but to do that i need to erase the part that is going behind the door so that it looks like hes gone in. Ive converted it to frame by frame and made them all bitmaps however i cant erase it and when i do modify>Trace Bitmap It gets rid of alot of the detail on the characters shirt. Is there another way i should be doing this.
It's much better and more flexible to use masks for this.
Trace bitmap is the absolute wrongest way to go about this. As mentioned masking is probably best, but you can also slice and dice bitmaps by breaking them apart (ctrl-B), which converts them to a bitmap-filled vector shape.