ICloud: What if I accidentally delete all my address book data on my iPhone?

If I lose my iPhone, I can still easily get my address book data back thanks to iCloud.

What I'm wondering is: what if I accidentally delete all my address book data on my iPhone for example, would it sync with iCloud and also delete all the data on my MacBook?

I have learned that with any computer device no Information is lost even if you completely erase the hard drive because with the right amount of money just about any computer related company can restore it. Just look at how hackers can still retrieve information. Of course one possibly secure way to discard computer information is to just take a hammer and break the device into many little pieces.