Wallstreet Theme comes with 5 Dark and 5 Light preset colors and Dark / Light background skins. You can find this setting in Theme Appearance Customize. You have to no need any code customization. In this theme we just want to offer visitors color variations.
1. How to Change Theme Color Scheme?
Go to => WP-Menu => Appearance => Customize => Theme Style Setting
Here you can see the Theme Color Schemes and Background (Light and Dark). There are 10 colors for choosing. Refer attach screen shot.