Yes it’s possible to manage group members if you are group manager.
To manage a group:
Go to the user workspace (cog menu → manage users and group)
Select the group you want to edit in the left side bar
Click on the tree little dots → edit group
If you are not being able to do one of these actions it is possible that the admin restricted them using the RBAC feature. Best to check with your administrator if that’s case.
Let us know if we can be of any further help.
Cheers,