There are two ways that I know of to get rid of it,
1. go to System Preferences>Accounts, click on your account tab on the left, then click Login Items tab on the top right, choose what you want to start up at login and what you don't want to start up by checking and unchecking the boxes.
2. Open up your Startup Disk, go into Library, then StartupItems and delete what you want to get rid of.