Perhaps you forgot to add some details to the Task, or you need to change why the Task was created. You can do so by editing the Task.
Go to the Task you want to edit and click
and select Edit Task. 
The Task Edit screen will appear. Here, you can edit the Task details. You'll be able to edit everything about the Task, including:
Date and time the Task is due.
Assignee (an Inbox or particular colleague).
Click Save Task.
Tasks cannot be deleted
A Task cannot be deleted once it’s created. It can only be closed.
Task comments cannot be edited
The primary Task can be edited, but subsequent comments added to the Task cannot be edited or deleted once posted.