If a trip has been scheduled to a vehicle or tour and you need to unschedule it for any reason follow these simple steps.

Hover over the trip you would like to unschedule and click on the Status name in the upper right.

Select "Unscheduled" from the drop down.

DispatchBot will ask you to confirm if you want to unschedule the trip.  Click "OK".

Your trip will now appear in the unscheduled queue to the left.