If you want to deregister, you can do so from your personal data accessing Access my data> My Data.
Scrolling down, on the bottom of the page you will find the Deregister from the online store option.
When you do so, you will receive an e-mail confirming that your username has been deregistered in the application.
If you are also a Mundo Consum user and you deregister from the online store, you will not deregister in Mundo Consum.
It will only result in your username being deregistered in the online store.