Now, from the main menu, navigate to the View/Edit Classes section under the Classes heading:
From there, click on the Semesters button at the top of the screen:
Now, click on the Days Off link for the semester in the list that you want to remove the holiday from:
Finally, click the trash can symbol at the beginning of the line for the date/holiday listed to complete this process:
NOTE: It may take a few minutes before the session is restored to the classes for that semester. If you look up the class and go to the View/Edit Sessions link in the top-right "More Actions" box, then you can view the available sessions.