When you choose 'file' & then 'print' ('or control + p' or whatever way you normally print), when the print dialogue page pops up there should be a 'properties' button beside the printer name.
Click the 'properties' button, then choose the 'Paper/Quality' tab, & you should be able to choose 'black & white' there. Then click 'ok', & 'ok' on the original dialogue pop up page.
Your system might be slightly different, but that's a rough guide what to do. I don't know whether or not you can set b&w as default, I can't on mine but yours might give you that option.