If the bushing is spinning in the arm, the arm may still be good, but the bushing is shot, and the bolt may be too.

The bolt is rusted to the metal sleeve in the center of the bushing. The sleeve is supposed to be bonded to the rubber, but it isn't anymore.

Plan on getting (correct) replacement bolts as well as bushings. You may or may not need the bolts.

If the penetrating oil and a hammer doesnt work, and nothing else you try does either...

Cut the bolt off at both ends with a sawsall or hacksaw... cut next to the bushing to the inside of the crossmember, or grind the head and nut off with a grinder. Make sure the spring is out already.

Then you can clean up the arms and have the bushings etc... done. Put it together with new bolts and you got it.

An alternative to try to save the bolts...
cut the outer sleeve of the bushing and carve out the rubber until you can see the center sleeve. Turn the bolt until you can see the roll line of the center sleeve, and spread it open with a cold chisel, then hammer out the bolt. Penetrating oil can help here too.
If you have a torch and a water sprayer, and dont mind rubber fumes and fire, you can cut the outer sleeve and burn the rubber, remove it, and heat the inner sleeve, spread it with the chisel, and tap the bolt out.

If the shank of the bolt is rusted badly, it has lost diameter and integrity, and ought to be replaced anyway.