For now, I keep it in. Melting the cups is a good idea, I'll keep it in mind. Thanks for the tips!Great progress on the frame!
It was probably powdercoated, that is hard to remove!
If you really want to remove the BB, you need to melt the cups and then hit it with a hammer so the bearing shell comes out (of course you'll need to replace it afterwards). The with a hacksaw blade you can saw the piece that's still in, in half and pry it out. It's a tedious job, but doable. I've done it many times with those BB's
It's a common problem with brackets, they use no grease when they assemble it.