Filtering LifterLMS's default difficulty levels

custom-default-difficulties.php

<?php // Do not copy this line into functions.php

// copy from under this line

function _my_llms_custom_default_difficulties() {
	return array(
		'Gold',
		'Silver',
		'Bronze',
		'Any other name',
		'and so on within quotes and followed by a comma',
	);
}

add_filter( 'llms_install_create_difficulties', '_my_llms_prevent_default_difficulties' );

prevent-default-difficulties.php

<?php // Do not copy this line into functions.php

// copy from under this line

function _my_llms_prevent_default_difficulties( $difficulties ) {
	return array();
}

add_filter( 'llms_install_create_difficulties', '_my_llms_prevent_default_difficulties' );