Need ability to delete users from User Management

I’ve been running into issues where we have users in my environment that have duplicate Usernames but different SFDC User IDs, however when I compare them to their Salesforce counterparts the usernames are different.  I have to assume this is due to some upstream issue - changes made in SF that are out of my control and/or occurred before I came here - but this causes issues for me because the Salesforce Connector user job won’t allow me to use the SFDC UD as an upsert key, so I end up with partial failures related to the duplicate usernames (my upsert key).

When I run into these types of situations my only recourse is contact Gainsight support to delete the user for me.  I need more control over my user table with the ability to delete users.