You're not permanently planning to uninstall it, right? Are you trying to fix a botched upgrade, or 'downgrade' to an earlier version? I'd just download it from Apple's website and reinstall it.
Why do you want to get rid of iTunes? Getting rid of apps, with the exception of some preference files (and in this case the iTunes library) simply involves dragging the app out of the Applications folder and into the Trash. It will require deleting as an admin, or an admin's password.
well you see i wanted to put it on my external hd but i found out you cant install it on the external so i tried that but it still says its installed on the computer and i dont know how to uninstall it. i dragged and dropped the application from the folder to the trash but it still thinks theres something installed did i do something wrong and yes i still want to use itunes
Okay, you might need to remove the iTunes receipts (they'll have iTunes in their name and PKG as the file format) from the Receipts folder in the Library before being able to reinstall iTunes. Spotlight should be able to find these. Just look for iTunes.pkg, hold COMMAND (Apple key) as you select it from Spotlight and it'll take you to the right folder.
However, it's always best to keep the apps all in the Applications folder. This isn't the case for all apps but it certainly is for some. You can keep the iTunes app (which is relatively small) in this folder on your internal drive but still keep your music on the external drive if that's what you're after.