Are the cancel buttons not working? You should be ale to edit and delete it and or send it on. Is it an email that was created on your iPad? It should not really make a difference but you could try removing the app from open applications on your taskbar (double tap home bar) then hold your finger until it wobbles and hit the cross this will just remove it from your open program's list. If that fails reset the iPad usually if anything hangs or freezes this is the best option, just hold both the home and power buttons until the apple logo comes on and then it will soft reset the device. Hope this helps.