Outlook Contacts - unable to delete contacts linked to another email

I have a few email accounts. In trying to accomplish something I have been messing up the contacts.


Now there are 2 identical entries in Outlook Contacts (both empty)

Contacts some-email-address
Contacts some-email-address

The email address linked to these contacts is still valid and used for receiving mail only. Very sporadically used for sending - maybe a few times a year.
The contacts are empty, rightfully so.

I wanted to delete one, but got a warning "Cannot delete this folder" blah blah.

Any suggestions?

Thank you!
Indeed, that solved the matter: launch Outlook whilst pressing the ctrl-key to get into the safe mode,

When selecting 'folder-view' (the ... - three dots at the bottom) I found out that the Contacts-folder I wanted to delete was in fact within the Contacts-folder, i.e. as a subfolder. Long story how it got there.

Note: r-click the folder > Delete still did not work.

Selected the subfolder in question and dragged it over to the Delete Items-folder and emptied that one.
(btw: within the delete folder nothing was visible)

Matter solved.

Thanks again!