In this template, there are already 6 colors available. And you can find those colors in css/presets/ folder. preset3.css is the default color. If you want to change the color, then just replace all the color code from preset3.css. And remove some code (showing in the bottom) from every HTML header file for removing the color switcher from real website.
<div class="style-switch-wrapper">
<div class="style-switch-button">
<i class="fa fa-sliders"></i>
</div>
<h3>Style Options</h3>
<button id="preset1" class="btn btn-sm btn-primary"></button>
<button id="preset2" class="btn btn-sm btn-primary"></button>
<button id="preset3" class="btn btn-sm btn-primary"></button>
<button id="preset4" class="btn btn-sm btn-primary"></button>
<button id="preset5" class="btn btn-sm btn-primary"></button>
<button id="preset6" class="btn btn-sm btn-primary"></button>
<br/><br/>
<a class="btn btn-sm btn-primary close-styler float-right">Close X</a>
</div>