how to delete my outlook email permanently from the system

Hello.

I am sorry for your loss.

In order to provide you with the relevant and correct steps, I need to know in what way is their email address is set up in your system.

Is it being used to sign into Windows? If so, do you have your own sign-in separately?

Or

It is being set up in a certain app, if so which app?

Or do you just want to close their account?

Sorry I have to clarify, as it can be interpreted in different ways.