Cannot deactivate a 'Closed' user account

Cannot deactivate a 'Closed' user account

Hello,

We have 17 user licences for CRM.

In our list of active users, there is one account classed as 'closed'.  It appears this user is taking up one of our licenses and we wish to delete or deactivate but there are no options to do so.  How can we fix this?

Thanks