Imagine this situation: you just imported your full schedule for this semester into your main Google Calendar when you decide make some changes to your courses or want to switch to an iCal feed. In this and many other cases it would be nice if Google provided any form of undo import option. Unfortunately there is no automated way of doing this just yet, so manually deleting all events seems to be the only option. Somebody came up to me today asking if there is any way of solving this problem, so i figured something out. All you need is the original ics file and a simple text editor.