Users cannot be deleted, only deactivated in order to keep track of all the transactions the user has made in CloseDeal.
If you are replacing a job position with a new person, create a new user for the new person. Then deactivate the former user or reassign a new role or store or region. Example 1: Joe was given another position in the company => reassign Joe to anew role, etc. Example 2 Michael left the company and Richard will replace him => Deactivate Michael user and create new user for Richard. This will maintain clear audit ability.