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

If abandoned, the event details will not be saved and any evidence logged, any related tasks and all assigned investigation steps will be lost.

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

You will be asked to enter the Event Reference along with a reason for the event being abandoned. This prevents an event being accidentally abandoned. The Event Reference is the code listed in the event title.

Click Abandon to confirm and the event will be abandoned.

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