Accidentally used plumbing flux on a PCB; How do I remove it to reuse the board?
I clean my boards from flux with isopropyl alcohol and a paintbrush , I'm not sure what is different about plumbing flux that could prevent it from getting cleaned the same way.

If the flux is not mented all the way maybe a hot air gun will help get rid the majority of it (melted it can be wiped easily or drip away) and then just wipe the excess.
Another idea is to try with water first in case the flux is water water-soluble and then use the isopropyl alcohol