If you don't like a YouTuber or don't want to see his channel anymore then you want to block this channel. If you block a Channel then your YouTube don't recommend you this channel anymore and also you can't see this channel anymore.
How to block a YouTuber Channel:
First of all open YouTube app then open this channel and you see three dots at the top right corner, just click on these dots and here you see the option to block a user just click on this and YouTube block this channel and if you also want that YouTube doesn't recommend this channel to you, you just click on three dots at the right bottom of this recommend video,here you will see the option to don't recommend this channel just click on it and boom this channel completely blocked from your YouTube app.