// Restrict tags creating by editors
function disallow_insert_term($term, $taxonomy) { 
	$user = wp_get_current_user(); 
	if ( $taxonomy === 'post_tag' && in_array('editor', $user->roles) ) { 
		return new WP_Error( 
			'disallow_insert_term', 
			__('Your role does not have permission to add terms to this taxonomy') 
		);
	} 
	return $term;
} 
add_action( 'pre_insert_term', 'disallow_insert_term', 10, 2);