Once you navigate to your member's profile, click on the Activity tab. Then, hover over the line of points you would like to remove.
A Void button will appear at the right. Click this button to remove these points.
If this does not work, or if you need to deduct points for a reason that is not voidable, you can go to the Add Points tab and manually deduct the points using the Misc. points option.
Be sure to include a reason so that the member and other staff users on your team know why the points were deducted.