Hi:

How do I log off Dropbox on my iPad so that other users can access their Dropbox?

I do not believe you can. Once the Dropbox is activated to your account it will always open to your Dropbox. In the settings in Dropbox you have the ablity to Unlink your iPad from the Dropbox account but that is a hassle everytime you want to switch. Best way is to navigate to the Dropbox.com site and log in other users from that point.