Golems are vulnerable to the needle arrows from the plains. Its still a lot of arrows, but its a reasonable kill, about 35-40 damage per shot give or take.
Other arrows do not seem to work well, if at all. It seems unlikely you have these yet.

they are really slow, but hit hard. if you can avoid being hit, you can slowly kill them.
you may be able to make one fall down a mountain. That usually kills stuff, but I haven't tried to drop a golem like that.