I can't stand how Photoshop loads your Swatch and Styles palettes with a whole pile of useless defaults. They gunk up a feature that should, by its very nature, be as pared down as possible. I try to keep custom palettes for the sites I'm designing because it makes my work faster and more consistent. If you're always grabbing the eye-dropper to get colors and copying/pasting layer styles, chances are you're wasting time and getting innaccurate results to boot. So what's a good Photoshopper to do?
You could select each color and style individually and delete them, like I used to do. But there's a faster solution that is so easy, you'll kick yourself. I've created two empty palettes for you. Just download them and follow the directions below.
To empty your Swatches palette: Open the Swatch palette, select the More Options dropdown in the upper right, and select Replace Swatches. It'll prompt you to browse for the new palette. Choose empty_swatches.aco. It replaces the default rainbow of colors with a single swatch of black.
To empty your Styles palette: Open the Styles palette, select the More Options dropdown in the upper right, and select Replace Swatches. It'll prompt you to browse for the new palette. Choose empty_styles.asl. It replaces the default monstrosities with a simple "no styles" style.
Need to clean up your swatches palette? I know I need to go through and pick out what you do want and know what you would use, and get rid of the useless ones that honestly will not benefit you.