Dreamer 101 is correct.If you are printing with CMYK on white paper,then no white ink is used it just leaves the area uncoloured so there is no need to remove the white from the image.If it intrudes over another image,use a clipping path. You could always work in RGB (so that you can use the filters),but keep the CMYK preview mode on,so that you can see how the final image will look even before you convert it to send to the printers. Or how about,working in CMYK then selecting a couple of white areas then using Select-Similar,which will select the remainder of the white areas on the layer and just deleting.