The color wheel goes from 0° to 360°  with complementary colors (red — cyan/green — magenta/blue — yellow) being 180° opposite from each other.  You can decrease the amount of any color in an image by increasing the amount of its complement on the color wheel—and vice versa.

Other interesting tidbits:

• 0° & 360° are the same color “Red”
• I start my sepia toning at 45°…  halfway between Orange 30° and Yellow 60° on the color wheel.

In Photoshop, using the HSL palette:
…with the “Colorize” box checked:

• the Hue slider range is from 0 to 360°.
• Moving the “Hue” slider will produce a monochrome image with the absolute degree of color to your entire image.  (left image below)

…in the standard mode (“Colorize” box  unchecked):

• the Hue slider range is from -180° to +180°.
• Moving the “Hue” slider will offset the colors in your image by the degrees of rotation.

(right image below)