I will add have you deflated the oleo? as a lot of these bolts hold the end caps in the strut so you may have pressure in the strut forcing the cap against the bolt.
You might try drifting it to see if it will move, BUT PUT A HEAVY WEIGHT on the other side of the mount to absorb the energy.. only do this if you know what you are doing....
another way if you can get it in is pop something like a bigger socket over the head and use something like a big c clamp to press it out into the socket...
Again as said what aircraft? so we can get a better idea to help you........