I'm sorry you have a nasty rooster on your hands. If he weren't nasty, would you want to keep him?
I have far too many cockerels at the moment, and two have started going after me and others on occasion. They are both very good breeding/exhibition-quality birds, and I was intending to use them in a breeding program and show them. I was mentally preparing to send them to freezer camp, but that would leave me with no rooster to protect my girls, and they are good protectors. (The other two cockerels are just plain ugly birds and not the color I want to breed.) I'm an expert at avoiding processing birds until I absolutely have to. My latest excuse, by far, is my best--I just had cervical spinal fusion surgery December 30th and I don't want to risk any blood or gore getting on my neck brace!
I've been in touch with some internet chicken breeder friends who work with this breed (Ameraucanas) and one has given me some really good advice. She told me my problem (besides the too heavy testosterone load for the number of pullets) was partly because they were juveniles with no mature rooster to teach them manners. She also said it was not too late and they still could be trained.
I had been doing things like walking towards them if they so much as looked at me funny and chasing them if they actually rushed me, but they are pretty fast and I'm pretty old, so I never did catch them to pick them up and let them know that they really were not as big and tough as I am. It wasn't working.
She advised me to take a light stick (I use a 5 foot long bamboo garden stake) and just poke them a little to make them move away from me. She didn't recommend hitting them, kicking them or hurting them in any way, just poke them and make them move out of my way fast. You know what? It's working. If one gets a little uppity, I grab a little bamboo pole (that I have lying all around my yard) and just chase him around and make him run and jump to get away from me. It is quite funny, because as this cockerel is running for his life, the pullets are underfoot hoping for a goodie.
The other thing she said was to not allow them to breed a hen in your presence. Top roosters never allow a lesser rooster to breed a hen. They run up and knock the offending rooster off the hen.
The little stick is not to hurt them, it is to be your feet as if you were a rooster. Alpha roosters use their feet to knock the lesser roosters off the hens or out of their way.
When I started this program, I had to carry a bamboo pole every time I went anywhere near where the free ranging Ameraucanas hang out. Now I don't. Once in awhile, one particular cockerel needs to be reminded he is the lesser bird, but I am not fearful of being rushed by any of them when my back as turned as I had been. For any "Dr. Who" fans, these cockerels are like Weeping Angels, the scariest monsters in the universe.
I keep these birds in my front yard, and I often am out walking in the yard and working in it. I just can't have nasty roosters.
The lady who gave me advice reminded me that this was juvenile behavior and might very well go away as they got older. She finds she gets this kind of bad behavior when she has too many juvenile cockerels she is growing out. An older rooster won't allow this kind of behavior to happen.
So, if you really would like to keep this rooster, think about the above. If you don't want him, don't give him to someone else. Slaughter him yourself and enjoy using him. You raised him, you know what went into him and why should some stranger get some really wonderful tasting chicken--nothing like the mush you buy in the grocery store!--for free. Slaughtering isn't all that hard. After processing your own birds, you will have a new appreciation for any meat you eat.
Good luck with your decision.