1. Download and install GLTF Exporter for Autodesk Fusion.
2. Run Fusion and load a model.
3. There is a new toolbar panel named 'GLTF Exporter'. 

It contains three ribbon buttons as mentioned below.

A) Export
      1. After selecting the Export option, a 'Save As' dialog box will display on your screen.
      2. Click on the Save button to export the current model to the GLTF file. 

B) Preferences
      It contains a set of features in which you can control the different parameters to get the desired output.      

C) About
      It displays information about the product. It provides the facility to activate your product license at any time.

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.

Unload:
       1. 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.
       2. Unchecking "Run on Startup" causes the add-in not to be loaded in future sessions of Fusion.

Uninstall:
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 10/11), just as you would uninstall any other application from your system.