Go to Payroll > Pay Run > Action > Manage Pay tab, select the correct Pay Group, Pay Period and Pay Run type (eg: Advance or Normal).
Tick to select the relevant staff for Payslip deletion, then click <Remove Pay>.
If <Remove Pay> button is not available, it is due to the selected Pay Period has been closed. If that is the case, go to Payroll > Pay Run > Action > Activate Run to reopen the Pay Period. Once the Pay Period has been re-opened, the <Remove Pay> button will be reflected.