I understand your distress at seeing the photograph of your grandfather's grave, and I hope I can help you understand what BG is all about.
Billion Graves is a platform that was developed some time ago, to take advantage of the GPS signals built into the earliest smartphones. The basic idea is that anyone can install the BG app on their enabled phone, go to any cemetery and take photos of the monuments and markers there. Thousands of people do this all over the world now. We are all volunteer user/contributors.
Once the photos are uploaded to the website, thousands of users have access to those photos to transcribe the information on the stones and add other information about the deceased person or their family history. Again, all the information is via the volunteer community, and contributors of history information. All of this is searchable for FREE by anyone.
BG is partnered with Family Search to share family history information across the platforms,
and many many cemeteries have had this process done already. I don't have access to BG's stats but I am a long time contributor/user and would guess it is in the many thousands by now. I personally have photographed and documented two town cemeteries, several church cemeteries and a number of family graveyards.
I will also tell you that personally I am very grateful to those in other areas who have photographed and documented graves in my genealogy work that I would never be able to visit, and I have had Thank You notes from others who appreciated the ones I had done.It is very much a usesr collaborative. I have ancestral ties to Wales, so hope that someday I will find the graves for the dead-end on that lineage.
The overall purpose is to photographically document as many stones as possible, as they are often the only trace left of a person's existence.This is very important to a great many people, for various reasons. Many church and town records have been lost or destroyed and an old stone may be the only proof of a person's life. Many of these older stones are in very poor condition, from age, weathering, vandalism, and poor maintenance.
I do hope this has eased your anguish and that you can understand and appreciate what BG means to thousands of family history workers.
If you really want the photo of your relative removed from view you will have to send a direct message to BG Support, including the full name of the person, the URL for the gravesite, the URL for the cemetery and some discussion of your relationship and why you want it removed.
No one here in this forum has the capacity to remove a photo once it is posted to the site.
With kind regards, DS