Recolouring a B/W photo is something different to removing all colours but red.

Some digital cameras have this affect built-in, but it's fairly easy to do in photo editing software and particularly RAW developers like Lighroom.

If you have a B/W photo and you want parts to be red, you can clone the photo, slice the objects to be red from the top copy and change the contones but you won't get a very realistic result this way.
Basically, you'd start with a full colour image and remove all but red.