Hi, I just went through a similar situation about 3 months ago. I purchased three pullets and come to find out one of the chicks was a Roo. Of course, it had to be my Pet. He was the most adorable creature ever. I tried for several weeks after he started crowing to find a home. I finally had to resort to taking him to a feed store where someone else wanted him for their hens. I did a lot of research and found that nothing helped to stop the vocalizations, as a matter of fact, he crowed more when I tried to stop him.
I went to my neighbors and explained the situation I was in and asked for a bit of time, they were very nice about it and gave me the time I needed to find a home for him. One thing I did was keep him inside a cage in my house with a towel over it until the neighbors left for work in the mornings, then I would take him out and put him with the hens. At night, I would pull him off the roost before I went to bed and bring him inside. Its a lot of trouble but it can buy you some critical time so you can figure out where he will be going.
Good luck I hope you find a nice place for him to live. Please let us know what you find out or decide to do.