On the assumption that this is square taper, moderate success can be had using a "tuning fork" joint splitter plus aplication of a hmmer. Heating the joint with a carefully directed blow lamp flame can help too. Some say a gear/flywheel puller does the trick , but I've never managed to get one to fit around the arms (legs?) of the crank spider.
Judicious use of a dremel/disc cutter/hacksaw will get it off too, but the part is obviously scrap after that. It's scrap anyway, as the thread has stripped.
Getting the BB out requires (a) suitable BB tool (ii) BOLTING IT IN PLACE (3) application of lots of torque in the right direction.