You can always deactivate the Mobile App for Inventory Management Plugin from the Purchase Subscription Screen.
You can approach this screen either from the Plugins Screen or from the Manage Account Section.
If you are coming from the Plugins screen, you need to click the Deactivate button on the plugin tile labelled Mobile App for Inventory Management.
If you are coming from the Manage Account section, navigate to the Already Active section on the Plugin Subscription screen. Remove the tick from the activation checkbox to mark the plugin as Inactive.
Upon deactivation, all the features and functionality added to the application are removed. However, you can always choose to reactivate the Plugin without incurring any additional charges during its subscription cycle.