WP User Manager - Remove the user nickname from the Display name dropdown in the Account page

wpum_remove_user_nickname_from_account_display_name_dropdown.php

<?php

function my_wpum_get_account_fields( $fields ) {
	if ( isset( $fields['user_displayname']['options']['display_nickname'] ) ) {
		unset( $fields['user_displayname']['options']['display_nickname'] );
	}

	return $fields;
}

add_filter( 'wpum_get_account_fields', 'my_wpum_get_account_fields' );