[Update 09/26]
We are happy to inform that you can now edit, and delete background images as well from WorksManager. This means, when you delete a background image from WorksManager, it will get removed from all the data collectors within the project on next sync. However, please note that this functionality works seamlessly only with data collectors running Siteworks v1.73 or above. So, please upgrade to the latest firware if you want to make use of this feature fully. For lower versions, after removing from WorksManager, you have to manually remove the background image from the data collector as well before the next sync, else it will push the data back ...