Is it legal to have by default a super user account in a product

I'm currently developing a web application that I would like to sell worldwide ( It's a Document Management System). For debugging bugs, it would be very helpful to have a default Super Admin Account that I'm the only one to have access to it.

Legally speaking, is it ok to do this ? Knowing that I have no problem putting it in the contract, it's kind of an official backdoor...