Some things, like deletions of tests, can be limited from the workflow even for TDAdmin users.
Of course, in a normal project TDAdmin users can modify the worklow if they know how to. But if you have the ALM version and the project is associated with a template, that road can be closed for TDAdmin unless they are also administrators of the template project.
It is also possible to limit the access for example to customize some lists by directly modifying parameters in the project database.
So it all depends what you are trying to do.