I have managed to remove decals under clear coat by heating with a hairdryer until the decal got soft, then picking at the edge, until I could peel the sticker off. The sticker will leave a lip of clearcoat around the edge where you removed it. My frame was matte clearcoat over gloss black, so I could just sand the edge smooth with wet and dry, then respray.

Being a matte finish meant you can't really see the paint job. If you have gloss or metallic under coat, you are not going to be able to sand out the lip. You may get away with some neat gloss clearcoat, doing thin coats to build up and blend over the edge, but you will still be able to see where the edge of the decal was due to the resulting lump in the finish.

You will never be able to remove clearcoated decals and achieve a factory paint finish without stripping the frame, but you will be able to have it pass from a distance and eventually, the frame will be banged up enough for you not to give a damn.