the only way stuff like that might come off is to heat the vinyl with a heat gun, carefully pick away at an edge to get started, and peel each letter off
not much chance of getting it all off, especially if the lettering has been on for a long time - also remember that the paint under the lettering has been protected from UV, so if you do get it off, the difference in the paint will make it look the same as before!
much easier to just sand the doors and repaint
Bill
