You have noticed that the remove Self from group membership feature does not work in the 6.9 WI. The Remove button is disabled and users cannot delete themselves or other members from the group.
This is a product defect (TF00590354).
This Product Defect (TF00590354) has been fixed in the latest available maintenance release, you can get more information from its ReleaseNotes:
Active Roles 7.0.3 - Release Notes
ActiveRoles 6.9 Generic Patch 4 (206303)