How long did you leave the ELO before wiping it off? It can take a long time.
You could also try Naphtha. VM&P Naptha, Ronsonol lighter fluid, or Coleman camp stove fuel.
Either way, cut a small piece of paper towel the size of the lettered area (smooth toilet paper works well), place it over the lettering, and moisten it with the stripping solution. Leave it there for at least an hour. ELO will not evaporate, but you might have to reapply Naphtha multiple times as it evaporates. Hopefully that will soften the paint enough to be able to wipe it off.