You will probably get lots of good advice for managing this situation on here but personally if a rooster wants to attact me or mine without a real reason for the attact I next determine to find out how good he tastes!!
If you do want to keep him I have some questions. Are you male or female? Are you the primary chicken care taker. Do you have children? Do they or others also take care of the chickens? Are your chickens penned or free ranging? Actually I don't want to know the answers but they are some things to consider when you are making a decision about retraining or other plans. I don't think it is fair to rehome a mean roo. Can you think of a reason yours might have attacked today? I had one attack when I went to the pen with a bucket and shovel to get some dirt for the garden. Another threatened my grandchild who was unintentionally harassing the hens because he was close to the hens and carrying a stick in his hand. That rooster never became a problem, he was doing his job and I made sure the grandkids knew what the roos job was. The first one was a mild problem but neither of these actually attacked and successfully spurred or pecked. The ones who did that were culled.
