Once you sell something or give it away, you lose control. That is a fact of life.
If you want to keep them, you can create a bachelor pad. That is a pen where only roosters live. No hens at all allowed. They will pretty much get along same as a flock of pure hens if there are no ladies around to get the hormones flowing. You'll still have the same pecking order issues that you would have with a flock of pure hens but you should not have the breeding rooster aggressions. I'm not going to tell you that this will work out perfectly for you. Sometimes flocks with only hens and no roosters still have chickens die because of pecking order issues. They are unique living animals with their own personalities. No one can tell you what will happen, just what our experiences have been and what you can expect to PROBABLY happen. Chickens and their behaviors are not consistent.
Not knowing how many roosters you have compared ot how many hens, I'm not going to tell you that you cannot keep several roosters with your hens. There is no magic ratio that eliminates all potential problems, nor is there a magic ratio that assures you will have problems. That 10 to 1 ratio you see a lot is the ratio commercial operations use to assure fertility using the pen breeding method. It has nothing to do with overmated hens or roosters fighting. But the more roosters you have, the more likely you are to have problems, so my normal advice is to keep as few roosters as you can and meet your goals. And even then, you might have to make some hard decisions.
