It depends on the way it was attached. Most are blind pinned and silver soldered. To remove the blind pin, you will have to grind into the comp and destroy it. There should not be too much of a legal issue as long as you do not reassemble the gun with the comp off. Remove the comp, FSB, replace with a free float and new comp. Make sure you attach the new comp/FH in a "permanent" fashion.
Remember, silver solder alone does not qualify as "permanent".