Employee wise Revision: 


Go to Employees >> Click More >> Under Salary Revision Management >> Click Employee Wise Revision >> Select the month and Employee Code and click Delete



Bulk Revision

In the same path, select Bulk Revision >> Click List >> Month >> Code and Name >> click Search >> Check/Tick on Particular employees and click on Flush


Note: If an increment is being processed and payroll month is locked (example: July) later that specific month’s increment data cannot be deleted/modified.

 So, before any modification do unlock the payroll of that month and delete.

http://support.paybooks.in/support/solutions/articles/4000093080-why-when-and-how-to-unlock-payroll-