Hello Hirama666
What you are asking is not possible.
But what is recommended is the following:
Your sub admin should not be able to
1. Edit his own profile
2. Create user of the administrator profile
For this, you can uncheck Can Edit for the Users > User Info > User Profile permission.
This way, the sub admin won't be able to edit existing users' profile AND won't be able to create users with the "Administrator" profile (only parents and teachers).