If you are a group leader, there are two ways you can ban a memberfrom your group.
The first option is to click on the "Members" tab in the group and search for the memberyou want to remove or ban from the group.
Once you find them click on the "moderate ∨" button next to them. From that drop down menu you will be able to remove or ban them from your group.
Alternatively, a group leader can ban a member right from a comment that they made. To the right of each member's name, there is a link that says "options". Click on that, and the options "delete", "ban", and "close" pop up. Click on "ban", and the memberis banned from your group.
If you remove a memberfrom the group, all of their posts will remain in the group. If you need to moderate a recently banned member's posts, you will have to do that separately from banning them.