larliebler-
Many people call it the "white panel."
Generic removal instructions:
1) Drain what connections you can.
2) Disconnect water connections on front and rear of panel. The upper-left water connection will be a reach.
3) Remove door latch and gasket, if needed.
4) Remove screws.
5) Grasp panel firmly and try to remove. Usually, have to tip in one direction or multiple.
6) Remove remaining connections.
Take notes on the exact sequence, or you may have difficulties putting the panel back in.
Here is a post I made concerning wet bay renovations on our coach.
If I were you I would hold off on doing this until I fully understood the issues, if any with the black tank level monitor and its sensors. It could be that your monitor and sensors are working fine.
On the other hand, I haven't seen a wet bay that (behind the panel) couldn't benefit from a clean-up.