After logging in to Autodesk® Fusion 360™ go to the visual style section in your graphics screen, and click on the button that correspond to visual style you want to see.

Customization of visible buttons is done by Visual Style Setup menu below original Visual Style menu.

Install:

The installer that ran when you downloaded this app/plug-in from Autodesk App Store has already installed the app/plug-in.

OR, simply double-click the MSI to install the app. No need to exit or restart Fusion 360.

Uninstall:

You can unload the add-in without uninstalling it by clicking the "Stop" button when the add-in is selected in the list box on the "Add-Ins" tab of the "Scripts and Add-Ins" dialog.

Unchecking "Run on Startup" causes the add-in not to be loaded in future sessions of Autodesk® Fusion 360™.

To uninstall this plug-in, exit the Autodesk product if you are currently running it, simply rerun the installer, and select the "Uninstall" button.

OR, you can uninstall it from 'Control Panel\Programs\Programs and Features' (Windows 7/8.1/10), just as you would uninstall any other application from your system.