Sounds like the text was painted on. I'd suggest the use of abrasion like a nylon brush to go at it and see how much you can remove. I suspect you can also use chemicals such as rubbing alcohol to remove the text. Any stronger chemicals may also eat away the frame color(s) unless it was injection molded.
I use acetone free nail polish remover on nascar die-cast cars dozens of times and it takes the lettering right off without hurting the base paint at all. Not sure how it would work on plastic but thats where I would start.