The other end of this control arm is disconnected and hanging so there shouldn’t be any tension left on this side. The bolt just spins in place but won’t come out. I tried hitting with a hammer but I don’t want to mushroom the threads of the bolt
The bolt is rusted inside the steel sleeve and the sleeve is spinning inside the rubber bushing.
Apply copious amounts of Kroil or Acetone/ATF mix and allow to penetrate between the bolt and sleeve.
Use a C clamp and a deep socket to press out the bolt.
Put the nut back on the bolt to protect it. Hit the nut not the bolt. Above post is a good idea.
You can also try to spin the bolt and hitting the nut on the bolt at the same time.
Yeah, hammer time. I'll just add, don't think because it won't pop out on the first few hits that you need to hit harder. Give it some good smacks, with a sacrificial nut or two on the end, but just keep at it. The vibrations you're sending through the bolt will eventually break the bond between the sleeve and bolt. It just takes time.