1. An image processing system comprising: a scanner coupled to a processor that executes instructions to perform operations, comprising: controlling output image data of a color information extraction sheet including a specific area; extracting color information of a color to be removed corresponding to the specific area, based on image data which is obtained by reading, using the scanner, the color information extraction sheet on which an image is formed with a material of a color to be removed; designating a color presented in an original document as the object to be removed; and forming, based on the designating and the color information extracted, an image by removing the image data in the color to be removed from the image data of the original document.