Depending on your host control panel, you will usually find it in your hosting account somewhere. Usually the login/pass is the same as your hosting account login details. So be sure you really trust this person, as they could gain control of your entire hosting account. Sometimes you don't have any other choice. When they are done, consider changing your hosting account password, check your admin table in phpmyadmin to make sure they didn't add another admin they could use to get back in later. see more And if you are really concerned afterwards change other passwords associated with your hosting such as email passwords, ftp passwords, etc. And your Dolphin admin password too it's md5 encrypted, but heck you never know.

This is always a good idea, but I am more of a security freak than most I guess you could say.