Some catalogs online here https://dawescycles.wordpress.com/catalogues/

To my eye at least yours looks like a Galaxy.

You tap on the end with the threads and the cotter pin pops out the other end. Then the crank comes off. You probably don't want to deform the cotter pin though, if you want to use it again. They could be very tight on there. Maybe search for cottered crank removal for tips.