Once you have created events, it is a straightforward process to delete them from your calendar. You simply tap on the event and then choose the delete icon via the top-right corner of the screen. Be warned, though, that once you have hit OK, the event is gone from all synced devices.
However, if you log into your Google calendar via the desktop browser and then enable the ‘Sync to mobile’ option, there is a period of time when you can undo the delete. Simply click the calendar entry and choose Delete, then quickly select the Undo icon at the top to reverse the process.