Under Management > Leave Approvals, if you change the view to looked at Processed leave, the Approve and Decline columns become Unauthorise and Delete.
Unauthorising can then allow the employee to make changes to the request, such as selecting a different leave type or modifying dates and times, before resubmitting.
Deleting the request is used when the employee no longer wishes to take that leave. It will automatically Unauthorise the leave as part of the process.
Once you've selected and applied an action, you will get the following confirmation screen. Comments can be added to the employee for an internal notification before clicking Confirm.