When clean URL are enabled, the page at admin/config/search/clean-urls is like the following one:
When clean URLs are not enabled, you should see a description such as the following one, and a button to test the clean URLs ("Run the clean URL test"):
Use URLs like
example.com/user instead of
example.com/?q=user. If you are directed to a Page not found (404) error after testing for clean URLs, see the online handbook.
Once you click on the submission button ("Run the clean URL test"), Drupal would check if the clean URL are possible to enable, and show you the checkbox to enable them, which should be not selected.
If that doesn't happen, the online handbook reported in the description has a link to How do I unset the clean URLs? where three methods are listed:
- Run the following Drush commands:
drush vset clean_url 0 --yes
- Run the following MySQL commands:
UPDATE variable SET value = 's:1:"0";' WHERE name = 'clean_url';
DELETE FROM cache;