Removing ceramic coat from glass?

The dealer that I bought my car from gave it a ceramic coat. I know not what brand. Seems to be holding up very well. However....

They coated the glass. Beads up really nice, but my automatic wipers don`t work very well. Found in the owner`s manual that you should not coat the windshield in the area of the sensor (right behind the rearview mirror) with anything, as it will prevent the wipers from working correctly. And they are right! Seems the optical sensor is looking for the refractive difference between dry glass and glass that has an even coat of water on it. Glass with beads of water isn`t cutting it.

I just need to clean an area of maybe 3" square. I`ve tried isopropanol, which seemed to have no effect.

Ideas?

Thanks,
Hans.

Very fine steel or brass wool. 0000 or finer used with window cleaner.

Polish the small area with anything abrasive, preferably via machine but f you have a 3” or smaller pad.