There is a permission SuB Administrator in AR System,
which is having limited access in AR Admin tool.
The Sub Administrator user wont't be having the access to Administration forms
You can check that
If you are running on ITSM 7.1 and in case its only limited data updates then you may able to get away from this by giving assigning the User appropriate access. I do not think that you need to be an admin to add people to support groups.
A long term solution would be, if you execute such house keeping tasks very frequently, you can have some customization in place so that memebers of group say "Data Admin" can also do this.