Put me in the "clicking the link and monkeying around with the reservation is nowhere near as easy as just clicking delete" camp. Seeing one more email in my box doesn't notably alter my quality of life in any way, so why should I ruin someone else's vacation?
I've had someone mistakenly give my gmail address as theirs to a number of folks. Travel sites, banks, their mother. I think the thing that irritated me to most, was that their mother sent me some information about a trip and contact info that she obviously wanted her son to have, and I bounced it back to her with a note saying that I was not the person to whom she was actually emailing, and I didn't even get a thank you. Bah. The sad thing is said impoliteness won't stop me from continuing to do the right thing.
If it's likely that it's just a typo, I wouldn't punish them; I've certainly made mistakes like that.
I would contact the hotel and let them know about the mistake. It's entirely possible that they have a phone number as well. They also probably have other resources, such as credit card, for tracking the person down. Worst case, they would know that the email they thought would reach that person was invalid.