Convert From Full Colour to 1 Colour???

Hi Everyone! ☺

Please help!

I sent artwork over to one of our suppliers for quotation books that I need to print for a client.

They told me I have to amend my artwork from full colour to 1 (one) colour before they can start printing.

Can anyone please tell me how to do that?

I know it's probably just a few clicks & it's done but I have no idea...

Any help would be highly appreciated - I have X6 & X7.

Zuné - South Africa