What Chris said. If you start with the solvents you are not really going to free the decal, rather you are going to melt the future which may by proxy get the decal off but quite possibly leave you with a mess if you overdo it.
Conversely, MircoSol cant hurt and may soften the decal enough to get it off, though I can say from experience that decals applied with MicroSol and left to dry can be very stubborn to get off, even though they may not be sealed with anything. Just depends of the quality of decal itself, how it was applied, and to what substrate.
I would try the MicroSol which will probably get most of it off leaving a few flakes which I would then carefully go at with some 1500 grit. Worst case you have to re-varnish the area to get rid of any scuff marks.