When you mark an assignment complete it will show up as completed on your calendar.Once the assignment owner marks the entire task complete it will no longer appear on your calendar.icon and type the email address of the person you want to assign the task.
If you marked an assignment complete by mistake and need to re-open it you can go to the Smart Queue and click the checkmark.
This will NOT remove the user from any tasks that you assigned to them. Assigning a new task to the user will re-add them to the menu.
To head to Workast from Slack, click on any of the blue Task IDs of the tasks in a channel or by clicking on the "Open in Workast" button.
You can remove users from the Assignments dropdown menu by going to the Assignments tab in Settings and clicking next to the user you wish to remove.
(This is helpful if you mis-typed a user's email address).