This is a simple one.
If you’re using the website: go to their profile and click on “Block this member” in the left column.
If you’re using the new Grokio Communities app: go to their profile, then click on the three dots that are on the right hand side underneath their profile text. That will give you the option to report or block them.
If you’re using the old app: go to their profile and click in the upper right corner, then click “Block” in the pop-up.
Keep in mind that once you block someone, there’s a 72-hour waiting period before you can unblock them (this is to prevent abuse of the block feature).
Hope this helps,
The Grokio Team