ColorReplace

ColorReplace[image,color] finds regions in image whose pixel values are similar to color and replaces them with transparent pixels.

ColorReplace[image,color->replacement] replaces all pixels with the specified replacement color.

ColorReplace[image,color->replacement,d] replaces all pixels whose values are within a distance d from color.

ColorReplace[image,{color1->replacement1,…},{d1,…}] does multiple color replacements.

Please visit the official Wolfram Language Reference for more details and examples on core symbols.