Kidding. I used a toothbrush to scrub the area clean to erase the part that I did not like. The tape protected the area I wanted to preserve. I scrubbed away from the tape so as not to push water under the tape. I made sure to blot immediately with clean tissue so freed pigments do not have a chance to work its way back into the paper’s fibers.
Yes, it is okay to use tooth brush on watercolor paper as long as you are working on cold pressed or rough paper because you guessed it, those paper have “tooth”. 😀
Arches is a tough paper though so it could take this abuse without getting damaged. If you are planning to scrub mistakes with a toothbrush or with any stiff artist brush, be sure to test first on a scrap of that type paper before doing on the painting itself.
I was able to get the white of the paper back. Actually this part, I could have just hidden behind the mat. No need to erase. But for my peace of mind, I wanted it corrected before I sign it finished.