How to Clean Underbelly of TT After Removing Tape

Thanks everyone. I have to redo the underbelly tape job done by an RV service tech - I had the black water shut-off valve/&cable replaced, the original underbelly of the TT had to be cut into in order to gain access to replace the valve/cable assembly. After returning home, I inspected the underbelly repair, and found several areas where the tech applied patch tape which did not cover some of the cut seams. I also did not find the patch tape to be of good quality - it’s a long drive for me to haul the TT back to the RV service site, so I’m redoing the patch tape job myself.
Phil