If you have admin access to Drupal log in and go to Administer – Content – Content Types. Then edit the content type of your choice and make sure comments are set to off by default.

Alternatively the above can be done directly by executing the following query in your database:

UPDATE system SET status = '0' WHERE filename = 'modules/comment/comment.module';

When you decide to re-enable the module simply issue the reverse query:

UPDATE system SET status = '1' WHERE filename = 'modules/comment/comment.module';

Disable User Registration

UPDATE variable SET 'value' = 's:1:”0?;'  WHERE 'name' = 'user_register';