There aren't many reasons for an organization to completely delete a user. Deleting a user will remove all updates and tasks that individual user stored in Notebird.
The archived user status allows you to keep all the updates, tasks and milestones that specific user created without having to pay for their account to stay active.
Steps for deleting an archived user:
Click Your Name in the upper right hand corner
Click My Team in the drop down menu
Click Show Archived
Select the archived user you'd like to delete
Click Delete