change colour from tan to black

[TheBadger]

I want to change a colour to black (including all shades). If a part of my picture is red or tan, for example, I want to change it to black (like for a car or T-shirt). 

I've seen tutorials for colour changes using Rotate Colors, but these just handle RGB colours. 

All answers online do not address my issue, or they just assume I'm looking to change my pic to black and white. 

Thank you