Once an action has been created, it can be abandoned by any user with the correct permissions.  

If abandoned, the action details will not be saved and any updates or attachments added prior to the action being abandoned will be lost.

To abandon an action, from within the action itself, select the Abandon option from the top of the screen.

You will be asked to enter the Action Reference along with a reason for the action being abandoned. This prevents and action being accidentally abandoned.

Click Abandon to confirm and the action will be abandoned.

If you do not see the option to Abandon the action, then you have not been given permission to abandon actions. If this is the case, please contact your System Administrator who will be able to grant the relevant permission if required.