How to clean off the white of the plastic frame eyeglasses depends on what exactly the white is. If it is a kind of paint, you can try using the oliver oil. You can use the glasses cloth to be soaked with a bit of the oliver oil and wipe the white for a minute, then the white paint can be gone. You had better not use petrol because the petrol may make the glasses corrode. If the white is a kind of glue or greasy dirt, you can firstly use handkerchief to wipe it clean, and then use water to wash the lenses, or use cleanser essence to wash it out.
Well, generally speaking, there are many ways which can be used to remove the white off the plastic eyeglasses. First, you should clean the lenses thoroughly, using distilled water. And then, of course, you can dry the lenses with a lens cloth. And you should make sure that they have absolutely no ink, oil, debris or fingerprints on them. And then, place the lenses in the lens holder of the dye tank. Of course, you also need to place one lens on each side of the holder and secure them in place. Finally, just slowly lower the lenses into the bleach, or neutralizer, solution. In the end, you can just check your lenses, and maybe it can be ok. Anyway, just have a try.