Uninstalling

On the Home tab, find the Add-ins group and press Add-ins.

Press the "More Add-ins" button in the bottom right corner.

This will display the "Office Add-ins" dialog box and display the Store tab by default.

Select the "My Add-in" tab, which is the first one.
Find the add-in you want to remove in the list.

Right mouse click on the add-in to display a shortcut menu.
This is the same action as clicking the three dots in the corner.

On the shortcut menu choose "Remove".
This will display a message asking you to confirm.

Press "Remove" to remove the add-in.
The add-in has now been successfully removed and will be automatically removed from the list.