I need to delete data from firebase if a variable == 0, example, i have collection country, their sub-collection would be cities, then hotels. Users can upload a hotel for others to reserve a spot, and when each person reserve one, it decrement by 1 of course, i have that till there, my cuestion is when it gets to 0, i want that hotel to be eliminated and not longer shown in the listview, and adding a second cuestion how do I do when the number of suitcases for example decreases, when it reaches 0, but there are still spaces for people, this does not start to be a negative number, I mean like the min number is 0