You must be an Admin of a group in order to remove members from a group.
Go to the Groups page
"View" your group
Click "Invite Members"
Select from List, or Add Email
Note: If you are not the admin of the group, you may Share the group via Facebook, Twitter, LinkedIn or a link by clicking the arrow (see image below) - this link will bring non-members to the group, where they may ask to join.
Click arrow to share a group
How to Remove Members from your Group
You must be an Admin of a group in order to remove members from a group.
Go to the Groups page
"View" your group
Click on the "Members" tab
Find the member you wish to remove, and click on the three vertical dots on the far right beside their name
Click "Remove from Group"
If you are sure you want to remove this person, click the "Remove" button