How can I prevent?

If it is possible, I dont want my users to change their nickname color "red,yellow,green and purple".. How can i do this?

Adn also, how can i change their chosen color to default color (when they register)?

[KevinL]

Disable the 'color username' action in the admincp.

Change the html markup in the usergroup manager.

[turkforum]

Thanks for your quick response..
i want to able my user to change their nickname color but not to let them to choose red,yellow,green and purple because they are forum supermods and mods colors..