Since yesterdays shortcut had to do with the Eyedropper, it makes sense to me to follow with shortcuts for the Color Sampler tool. With the Eyedropper tool selected, Shift-click in the image area to set a Color Sampler. With the Eyedropper tool or the Color Sampler tool selected, Option (Mac) / Alt (Win) Shift-click on the Color Sampler (the icon will change to a pair of scissors) to delete.
