There isn’t any way in ACF to prevent empty values from being inserted.
If you really don’t want the values in the database then you need to create an acf/save_post filter https://www.advancedcustomfields.com/resources/acfsave_post/, check all the values and use delete_post_meta() https://codex.wordpress.org/Function_Reference/delete_post_meta or another WP function for deleting the value from the database.
