At the moment, I do not think there is a way to “hide” that detail view. That might be a good Feature request to submit.
However, you can control what is shown by creating your own view for the datasource that is shown.
If you are on a mobile phone device, the map view relies on a Deck view to show details. If you create a Deck view for the same datasource (table or slice) shown on the map, AppSheet will pick that to use instead of the default.
If on a tablet or a desktop/laptop, I believe you can do the same thing with a Detail view - creating your own that the map uses and then you can change what details are shown.
Images showing affect of changes in custom Deck view used by Map