Unprovisioning of the ProFTPD resource does not remove a logfile's association. Once the resource is provisioned back, an FTP user with the same username cannot be created again.
It is not possible to change Shared IP of the webspace to the Esclusive one in
CCPv1 > Websites > WebSite Configuration > Switch to IP exclusive:
Duplicate key violates unique constraint 'logfiles_associations_pk' while executing 'error executing work'.
The issue is acknowledged as FND-2685.
Contact your Technical Account Manager to trace the status of the request.