When paying employees there may be pay categories where you do not require the unit amount to show on the pay slip, for example paying a commission or bonus.
To hide the unit go to Payroll Settings > Pay Run Settings > Pay categories page and select the appropriate category.
Add a tick in the 'Hide Unit on Pay Slip' and click SAVE.
Even though the units will still be displayed in the pay run they won't appear on the pay slip as shown below.