the manufactor does not recomend sanding.  do a test panel you might be able to shave it with a razor blade and buff it

"When completed, the surface should not be cut or buffed as the finish cannot match the original gloss level. "

Thanks Dexter for your ideas, I tried the razor blade but with little success and I had read the manufacturers guide lines but read them that it could be lightly sanded but not the final coat. So as this was not my final coat I bit the bullet and proceeded to sand out the run whick ran the length of the deck forward of the cockpit with 240 followed by 400 grit paper. The results after a more carefull addition of clear coat appears to be excellent.

Try this sometime, when spraying the PU only apply enough so you have a good reflection of your fingernail in the surface.  That should be the right minimum thickness for a coat and avoid runs.  It worked for me.