In better HR, the dashboard users can adjust leave days accordance with your policy.

1). Go the 'Setting' by clicking your profile. 

2). Click on 'Policy' and select the policy you want to change.

3). At 'Leave', click the leave type you want to change.

4). Click 'Save and Regenerate' at the bottom of leave setting.

5). When you  see the leave adjustment preview, adjust leave days and click 'Confirm'.

6). Click 'Update Policy' and 'Confirm'

Please refer following tutorial video: