I had previously edited this photo, however the file was corrupted and I cannot remember how I edited it, and I can't recreate the same effect of the colour change. I am wanting to recreate the black and white art on the right, any help would be greatly appreciated! Thank you [
The easiest way is to simply switch to the channels palette, turn all but one of them not visible, and when you decide which you like, delete the other channels and then flatten the image and ensure the mode is correct (RGB or greyscale).
However: the black on the tongue looks more like a magic-wand selection; the brick background still has color in it.
In this particular case, the blue and red are very well isolated, so you simply "select color" for each, copy and paste to new layer to isolate, and then desaturate the color etc. etc.