There more and more people abusing the event system everyday, and it's just so they can get information, send mass messages, or worse: take over your account! So to make sure you don't aid these crackers you need to make sure you are removing the events, not actually doing what they want you to!!
You can go to the event itself and scroll down to the bottom and click on remove from my events, but do not do anything else on the page, do not respond, and especially don't click any suspicious links or send out invitations to others, that's how it spreads to such a large amount of people!
If you have email event notifications enabled, you can do it straight from your email!
Either way it will pop up a confirmation with the ability to ignore all invites from the person who sent it. Which might be a good idea if you don't know the person!
So help reduce the spam events by doing this and spread the word to your friends, with your help you can greatly reduce the amount of this garbage you see. People just don't know any better, so inform them!!