My sister downloaded a app on my phone using her ID now its in my updated list but i cantnot update it beacuse my sister account is no longer how do I delete it altogether?

Hold down on the icon until you see the icon wiggle and an X appear. Tap the X to delete from the phone. Did you sync the phone to the computer and iTunes? If so, the app should also be on iTunes. If it is, then delete it from iTunes before you connect the iPhone again, or it will download it to the phone again.

Or just uncheck it from the apps tab of iTunes. That will uninstall it.