If that person has a login, you can search for their name on google if you add the criteria "Mangago"- at least I have seen others tell people this - or if you see they are online here, you can click on their name and email them - there is a link at the top of the page. (little envelope)
!!?? You CAN'T delete whatever you didn't create.
You can easily send message to registered users by just click at their name.
Oops! mistake.. I thought about manga page.
Actually, you can delete other's message in your home page. (>‿O)v
How do I write a message to somebody? Cause I accidentaly deleted someones message