Painting, single stage urethane

[Farmer888]

So I painted a tractor using omni single stage urethane.
First coat went on decent, Got carried away on the second coat and got a whole bunch of runs and sags on the vertical panels. I'm not too picky on this since it's still way better than it was, but i'd like to try and clean up the sags. and a few other imperfections.
Whats the best route? it's been 2 days now, should I be sanding the sags out? I took a razor blade and started cutting the runs and still soft.. with the big sags I won't be able to save it without a respray.

What grit do I use on the sags? Then I'll have to lightly scuff the rest of the tractor too, what grit for that?
Thanks and Hopefully someone can weigh in here. I know not a painting forum but hopefully someone has some experience.

 

[Wrench97]

Wet sand with wet/dry paper is your best bet if still soft, 220,320 down to 600 before the respray.

 

[56Mark]

I have seen people put a thin skim of body filler around a sag or run, then wet sand the area and when you get thru the filler and see paint it is all smooth. I am sure there are YouTube videos of the technique.

 

[HMCFab9]

Sand with 600 wrapped around a paint stick to cut it flat.