That's exactly one of the benefits of free speech. A kind of inverse of the "remain silent and be thought a fool, or speak up and remove all doubt" saying.
Free and open discussion lets me know who's worthwhile listening to and who should be ignored.
You can say "no more" as much as you want. You can point out their foolishness. You can block their content from your life. It's all part of the same dance.
Without some kind of legal exemption, however, you cannot prevent them from saying more (unless you own the platform, but that level of control is limited only to the platform that you own).
Free and open discussion lets me know who's worthwhile listening to and who should be ignored.