How to change color of bootstrap glyphicon?

Use color

 <button type="button" 
      class="btn btn-info btn-lg" ng-click="serverFiles()"
      style="margin-left: 10px; color:#FF0000;">
          <span class="glyphicon glyphicon-folder-close"></span></button>

But remember that it is desirable to avoid the use of inline style is better use classes or references based on external css configuration items

 <button type="button" 
      class="btn btn-info btn-lg mybtn-blue" ng-click="serverFiles()"
      style="margin-left: 10px;">
          <span class="glyphicon glyphicon-folder-close"></span></button>

edn for external css

.mybtn-blue {
   color: blue;
}

You can also change the icon/text by adding to the class "text-success" for green, "text-danger" for red etc. This will change the color of the icon itself.

<span class="glyphicon glyphicon-usd text-success"></span>

Also this has been answered here.

Change the color of glyphicons to blue in some- but not at all places using Bootstrap 2

Use the following HTML code

<button type="button" class="btn btn-info btn-lg" ng-click="serverFiles()" style="margin-left: 10px"><span class="glyphicon glyphicon-folder-close yellow"></span></button>

And the css code

.yellow {
    color: #FFCA28;
}

here is the demo http://jsfiddle.net/S3R23/1217/