script for CMYK image convert gray color in Indesign cs6

I don't understand your English quite well, but as far as I can see, you may be interested in this script.

@Peeyush37849741

Convert in Photoshop - then update links. 

Of course, make a backup copy of all your images. 

I think I have a script to convert swatches to Grayscale if it's what you're asking, I don't have on this computer though, I'd need to wait to Monday to access it. 

I don't know such a script in InDesign. But if you want to convert the whole PDF document to greyscale you can do it in Acrobat Pro > Print Production > Preflight > Convert to greyscale. 
You can also convert a document upon PDF export if you choose a greyscale profile as output profile.