Select Cheque Books on the Settings menu, then the cheque book which contains the cheque to be cancelled.

Locate the cheque in the list, there is a search function at the top of the page if the list is long.

Click the button beside the cheque:

Select a reason for the cancellation, then click 'Cancel this Cheque' to complete the cancellation process.

After cancelling a cheque, the Status will show as Cancelled.  If Lost, Stolen or Other was selected this will show also.

Cancelling a cheque in Re-Leased does not cancel it at the bank!  Only cancel cheques in Re-Leased if they are not going to be presented in the future.