The uninstall process for the MessageMedia BigCommerce integration is managed from your BigCommerce store account, and to do this you'll need to be logged in as the store owner.
1. From the BigCommerce dashboard, go to Apps in the main menu and click on My Apps.
2. Now on the MessageMedia SMS Marketing tile, click on Uninstall:
That's it, you're done - there's no uninstall confirmation to select, no further steps are required.
The MessageMedia app tile will vanish from your BigCommerce My Apps, and the BigCommerce integration tile in the Hub will automatically reset the next time the page refreshes.