Need help to disable post revisions

I am trying to disable post revisions as I have use this code exactly same from the tutorial i have seen about WordPress disable post revisions but still I am having some issues. Can anyone tell how can I disable post revisions ?

  define(‘AUTOSAVE_INTERVAL, 300);

define(‘WP_POST_REVISIONS’, false);

define(‘WP_DEBUG”, false);

If I am going to put this code then it will stop further revisions. Can anyone help me on this ?

define(‘WP_POST_REVISIONS’, false);