There is no way to print color at all if there is one toner faulted.
Some printers allow you to print BW though, just make sure it is set to print in BW
And that the application you are printing from is not sending a color override, Acrobat/Reader for instance does this, so change it first ala File > Print > Advanced > Let Printer Determine Color
That may work, I don't have the particular printer to test for certainty that it is capable, but most are. The trouble is they all fault if they interpret a single pixel of color
I have a workcentre 6015 and when I run out of Cyan (for example) I can't print anything! How can I make it print without using the Cyan?