So, when I click on the ''Administration'' I got all the Group Information but is something more that says ''Pending Members'' Which is one user and I'm not sure what is that for and what it dose I'm also trying to delete it but it wont.

Pending members are those members who applied to get into the specific group you made. When you make new Group, there's option that says Opened group/Closed group/Hidden group
When you make it Opened, people can apply to be in it. You can deny the access or allow them to be in the group.

Thanks, I have move them from there.

You're welcome