If you accidentally add availability to your calendar, *you cannot remove it by trying to overwrite it with the add availability tool.* Example: you wanted to make yourself available Monday, Wednesday, and Friday and you added Thursday by mistake. To fix it, choose the day you don't want and click the red Run Pre-Delete Checks button seen above. Once you've confirmed that you don't have any LibCal appointments, you can delete the Thursday availability without having to delete everything and start over.