If you have set a task by accident, or you are simply finished with it, you can remove it from the "current" or "passed due" states using the "Sign off" button on the Mark work page.

 

 

You can also sign off multiple tasks by selecting them via the checkbox and clicking on the green button at the top of the filters to the right.

 
 

The tasks are now removed from the students’ list of work to complete, so issue any catch-up work, rewards or sanctions at this stage.

 
Signed-off tasks will remain in the "Signed off" category for the rest of the academic year (unless you undo the sign off). You can't delete them completely.
 
Please note that any student data related to the task will not be removed.