So-what did you do and why do you feel this way? Roosters' skin is attached very tightly, so that was one problem I had. I couldn't tear it off, but had to cut all those things that attach it to the flesh. Also, I had tried to shoot my first rooster (several years ago) with a pellet gun and the pellet just stunned him, then he went off squawking like a maniac. He was a real pia, so still had to finish the job. Then I cut myself pretty good and gave it up for that one. Felt like such a quitter!.
Let your feelings on this settle, analyze what went wrong. You may change your mind, I know I did.
As far as letting him loose-- I wouldn't. I had one young cockerel who I couldn't get to go roost one night, so left him out. Something got him and then, night after night, I had something nosing around. Was so worried he'd dig under and get in the coop! That made me reinforce my perimeter and resolve never to leave another bird out. This one that got left out had roosted on the top pole of my wooden swingset--should have been out of reach but wasn't.