Want to make Portal's Group Tag Read Only by not allowing people with access to the Portal to update the group tag.
All supported DevTest releases.
Need to remove Update Virtual Service Group Tag permission from role.
Update any role that a user has where you do not want the group tag updated and remove Assigned permission of "Update Virtual Service Group Tag".
or
Create a custom role for those users that you do not want to be able to update the Group Tag.and do not assign the "Update Virtual Group Tag" permission.
Refer to section "Manage Roles and Users" in the DevTest documentation of the version you are running.