How to remove all default Gutenberg block patterns

Below is a snippet that you can add to your functions.php file to remove the default Gutenberg block patterns.

function fire_theme_support() {
    remove_theme_support('core-block-patterns');
}
add_action('after_setup_theme', 'fire_theme_support');

This needs to be added to either an init hook or to after_setup_theme, and you will most likely place this inside a function, together with the rest of your theme support.

Solution source