Remap the undesirable original colors to the required colors, honoring the specified overprint settings. You can remap individual channels, color space or color at a time.
For example: If you have a PDF file which has all colors in Device CMYK and you want to convert these to Device RGB, then select Color Space and Device CMYK in the Remap: drop-down menus. Next select Color Space and Device RGB in the To: drop-down menus.
For example: You have a file which has objects composed in CMYK and Spot red. Suppose, you want to remove the Spot red then you can remap the Channel Spot red to another Spot color or CMYK channels.
Channels are blended with multiply blend. Depending on the color information in each Channel, the base color is multiplied by the blend color (that is, only the percentage of color which is required to get the resultant color is blended).
When you are remapping several channels to a single channel and those channels originally had a combined ink coverage of more than 100%, the result of the remap will never be more than 100%.