How we can revert our leave after approval

How we can revert our leave after approval in HR module.

suppose an employee have taken 10 days leave and after approval employee wants to cancel this leave OR employee want to cancel partial leave like 5 days from 10 days . so what is the way to revert that leaves to leave allocation.

Please suggest me solution .
Thanks

Approval means the leave application has been submitted. To make any changes, you would have to Cancel the application, make the changes and Amend