Removing post color? Where is it located?

[93Corvette]

This is such an easy question but I can't seem to find it anywhere...

One of my members is using the color "Pink Plum" and/or "Thistle" which is really hard to read on the board. How do I remove these colors off of my website so no user can use them? Where are these colors located so I can remove them?
Thanks...

[Stagehandspace]

Not sure you can remove single colors but there is the option to remove color bbcode

Admincp >> vBulletin Options >> BB Code Settings

untick "Allow Color BB Code"

Save