Please follow the steps below on your Macintosh:

Click on Go at the top of your Toolbar.

Then double click on Applications.

Look for the Garmin MapManager and double click on it to open.

Garmin MapManager will now list all the maps installed on your MAC.

Click on the map you wish to delete/uninstall from your MAC.

Now click on Map Actions > Delete. (That is the button in the bottom left corner of MapManager).

You have now successfully uninstalled T4A maps from your Macbook.