On Sleeper, we allow you to block other users from sending you direct messages and from seeing their comments.
Blocking somebody does not remove them from any leagues, but provides a way for you to avoid seeing any of their comments or chats.
You can block another user by selecting them from the league chat. You'll see their team come up, tap in the top right corner to get to their profile.
On mobile, you'll need to select the "More" option and then block:
On the web app, all you need to do is click their name or avatar and their profile will come right up, you can then click on block in the bottom right:
To unblock them, you will have to go to the web app. Click on Direct Messages in the top left, and then click on View Blocked all the way to the right.
This will bring up a list of your blocked users, and you can unblock them at any time: