Step 1
Go to Leave > Click on Leave Balance > Choose the Leave Type
 E.g. Annual Leave > Double click on the employee
Step 2
Click on New
Step 3 - Add/Deduct
Enter "6" if you want to add 6 days. 
Enter "-6" if you want to deduct 6 days. 
Read more:
HR can change employee's leave balance manually if the record needs to be adjusted.

Go to Leave > Click on Leave Balance > Choose the Leave Type
 E.g. Annual Leave > Double click on the employee
Click on New
Enter "6" if you want to add 6 days. 
Enter "-6" if you want to deduct 6 days.