Option to disable User Access Permission

We are currently evaluating Stash for our Git review and management tools as standard within our organization.
We have a requirement where we should only allow users from a LDAP group. Adding single users either from LDAP group or local stash should be prevented. Meaning all the users should come from a LDAP group.
Intention:
If project admin is allowed to change/add user & permissions for a project or to its own repositories, we do not control over users being used and we can not control the licenses. Our intention is to control the no of users at LDAP group and not at stash.
Somehow we want to hide/disable the "User access" tab in a permissions page, we only need "Group access" tab. We only need to either add LDAP group or remove in the project/repository permission configuration page. Adding a user should be only done at LDAP group and not at stash itself.
E.g.
A read/write permission to a stash project or repository must be granted an access to any user via LDAP group and not manually by project admin.