how do I eject Garmin from my MacBook Air...no mouse, no right / left click...poor vision

According to Garmin support https://support.garmin.com/en-US/?faq=oboLdLIfkY8cuY6jauRem7

Click the Finder "Go" menu in the menubar, then click "Computer" in that menu, then drag the Garmin device to the trash from the Finder window.

Open a Finder window (e.g., click the Finder icon in the Dock), then look for "Go" in the menu bar at the top of the screen.

For a complete guide with pictures, click https://support.garmin.com/en-US/?faq=oboLdLIfkY8cuY6jauRem and then click To safely remove the device on a Mac in that support article.