Delete zoom levels from an MBTiles file (set max zoom)

mbtiles_delete_zoom_level.sql

-- change 9 to whatever the max zoom level you want in your MBTiles

DELETE FROM tiles_data WHERE 
  tile_data_id IN (SELECT tile_data_id FROM tiles_shallow WHERE zoom_level > 9) AND
  tile_data_id NOT IN (SELECT tile_data_id FROM tiles_shallow WHERE zoom_level <= 9);

DELETE FROM tiles_shallow WHERE zoom_level > 9;

UPDATE metadata SET value = '9' WHERE name = 'maxzoom';

VACUUM;