At this time, there isn't a way for the system to automatically deduct points from an assignment if it is submitted past the due date. However, if you choose to reopen an assignment that has closed, you can deduct points manually from within the gradebook for those who attempted the assignment after it was re-opened. 

You can manually override a grade in the gradebook through the following steps:

While on your instructor dashboard…

1. Select Go to Course.

2. Select Grades in the menu on the left.

3. Select Turn editing on in the upper-right corner.

4. Type in the new grade amount.

5. Select Save changes at the bottom.