So we all get these calendar (iCal) invites which the MacOS/OSX Calendar app then notifies us about in its badge icon and on the '+' button in the app. But what if you don't want to accept or reply to these invites - annoyingly enough there is no way to just delete them without sending some form of notification.
So how to go about getting rid of them? Well there's actually a way to do it - You create a new Calender (File->New Calendar->iCloud) and just leave the default 'untitled' name, then you find those pesky invites and right click on them and assign them to this new 'untitled' calendar. Then you right click on the untitled calendar and select delete - it then finally asks you if you want to delete without notifications! Gone. Done.