To remove it, I use cut-off wheels for Dremel. If you don't have it, use a saw. Never cut with pliers, because you could break the piece. After cut, you can sand faster with Dremel.
To cut and sand resin produces too much dust, so you should use a mask. Also, when you cut the wheel could breake it and hit your face or an eye, so you should use protective glasses.
Pieces already cutted and sanded. These parts doesn't see it once assembled, so the look don't matter.
Before:
After:
Here appear some bubbles, we can fix it with epoxy putty. The great thing about epoxy putty is that it don't low while it dries, so if you cover the bubble, that's it, you don't need apply once again. In fact, you can cut the putty excess with a exacto knife just after applied, so once dried you don't need to sand too much.
That's it for now. Next time, fine sanding and... boiling water!!