While there is no way to do this single-handedly with the click of a button, the Global Leave Write-Off/Pay Off Utility can be used. The utility can be found in the Payroll and Leave tab, in the bottom Utilities section.
With this method, you cannot pay off a single employee's leave. To do so, it is recommended that you manually calculate this payoff, and pay it off as an adjustment in the payroll.
After clicking on the utility, you will then be required to:
Input the leave type that you would like to payoff, along with;
The number of hours that you would like to keep (say you want to leave each employee with 8 hours of leave, you would input '8' - if you want to pay-off ALL the leave, this value should be left as '0');
Write Off or Pay Off the remaining leave (in this case you would select Pay Off); and
Select in which roll you would like to Pay Off the leave.
Clicking 'Next' takes you to a screen where you can make changes to individual employees - for example, if an employee has requested to keep 40 hours of leave instead of the standard 8 hours that you set for all employees. This would amend the employee's 'Hours to Keep' value to 40. Clicking anywhere else will re-calculate their 'Hours to Pay-Off.'
If you are unhappy with any changes in this screen, you can 'Reset Data' (green box in the screenshot below) and this will reset the data to what it was prior to any edits in this screen.
'Back' (red box) will take you back to the previous screen.
'Process' (blue box) will process the data in the current screen.
You can follow a video explanation of this process here.