PI AF System Explorer- Unable to undo checkout done by an ex-employee. (userid not existing anymore)

In our PI AF Database, an Element was checked out by an employee who is no longer in the company. Current status shows the small "person" icon next to the element name,

If I make any change to any attribute, I get "Element 'ABC' with UniqueID '123456' is locked by user EU\f281651."

but if I try to do File/Undo Check out, I get message "No checked out objects exist for the database: XYZ"

is there a known method to remove this blocking?

Thanks!

Josep

SteveBoyko​  ?