Deleting a user from Flexi is not possible, as they are linked to documents that have already been issued. It is recommended to block the user and restrict the validity of the given username.
Navigate to the Tools - Users in Company module and open the relevant user,
on the Login Credentials tab, set the user's User Type to Read Only and the User Role to BLOCKED: Inactive Account,
on the Administration tab, restrict the user's validity in the Valid Until field,
save the changes by clicking Save and Close.