Is someone coming back from leaving? Awesome! He can get back to working immediately by firstly activating the archived account again.
Archiving a user is only possible for a Full User. So, make sure you have the correct rights before you start. Ensure that the right users have the right authority within project management.
How do you un-archive a user?
Go to the settings. You can get there by clicking on the wheel at the bottom left of the menu.
Then, you switch the user overview from 'active' to 'archived' by clicking on 'active'.
There you can see a circle to the left of the user photo when hovering over it with three dots.
In the screen that follows, you can make the choice to edit the user's data, or you can de-archive the user. Click on de-archive to make the user active again.
Do you want to archive a user again? Then read this article.