You can find the add-in under the GEARS panel in SHWIVEL tab of DESIGN workspace. 

For creating gears, you must run this add-in. The window has default parameters, so you don't need to set them at the start.

Install:

The installer that ran when you downloaded this app/plug-in from Autodesk App Store will start installing the app/plug-in. Or, simply double-click the downloaded installer to install the app/plugin. 

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 and Features' (Windows 7/8.1/10/11), just as you would uninstall any other application from your system.