Disable cache for a specific page

Disable cache for a custom page from route declaration.

If you want to disable cache for a custom controller (Custom module), You have no_cache option (YOUR_MODULE.routing.yml).
Example :
File : mymodule.routing.yml

Disable All Cache on Drupal 8

Open settings.php add these lines:

$settings['container_yamls'][] = DRUPAL_ROOT . '/sites/';
$settings['cache']['bins']['render'] = 'cache.backend.null';

Use drush with command drush cr to clear all cache