I would agree with Sriram, if you think you still might have some mold rub your finger over the area if you rub what you think might be mold off then you could use a soft brush and brush off what is left. As far as repotting tips, soaking the orchid in some water, pot and all, will soften the roots so that you should not do too much damage, there are plenty of video's online about repotting different species, that will give you an idea of how to do that. Good luck!