1. Use “Quick search“ or “Extended search“ to filter for the contact
  2. In the displayed contact detail section „Tags“, either …
    1. select a „Category“ from the drop-down and the desired tag to assign it to a contact OR
    2. click the ‘minus’ icon for each tag you want to remove from this contact
  3. => As soon as the tag has been assigned/removed, this change has immediate effect on the system.