The only way to take down someoene channel is to mass report videos and have them taken down. For every video taken down they get a strike, 3 strikes and the channel gets deleted. So hypothetically if you were to take someones channel down it would have to be will a bot to mass report videos from different IPs and account. Im not sure how much reporting you would have to do since that's not publicly available information.
Taking it down through copyright is harder/easier depending how you look at it. If its legitimate copyright and I would suggest looking into what copyright entails, then you can report on that basis. I am not quite sure how you go about reporting if it is a different process since I personally haven't been in that situation.
If your looking to copy strike them because you simply don't like them, its not easy since you wont have any basis when they counter claim that its not copyright. Plus I wouldn't recommend doing that because its just a shitty thing to do.
