This can be done without a plugin.

In the admin go to Setting > Customize back-end and there you select the Styles tab.

Then just add the style below to hide the icons:

nav#layout-mainmenu .nav-icon {
    display: none;
}

But that removes all the icons entirely. I just want to remove the SVG-icons, that way the CMS uses the Font-Awesome icons instead.

Oh, I see now.

Might be worth noting that it reverts to the Font Awesome icons to the plugin description.