how do I remove a user from my ipad

If you mean an iTunes store id then Settings > Store - touch the id on the right and select sign-out from the popup. You can also do it via the bottom of the Feature tab in the App Store app. If you have any apps on the iPad that were downloaded/installed via that id then you may want to delete them - if updates for them ever appear in the App Store then you will only be able to update them via the id that was used to buy them (apps are linked to the account id, not to the device that they are on)

Isn't the iPad a single-user device?