Removing a user from your community stops them from being able to access your community. They can still however access their account and any past sessions notes, conversations and any MindLab content that they already have in their library. You would need to send another invitation to the user if you wanted to allow them access again.
If you want to stop them accessing their account, suspend the user before you remove them.
DO NOT remove yourself from your own community!
Find the user(s) and select the checkbox next to their avatar
Click on More to see the dropdown menu and choose Delete from community
You will need to invite the user again if you wish to restore access.