You can disable showing of PHP warnings, either in server main php.ini or custom php.ini on the account.
edit /usr/local/lib/php.ini, and change error_reporting value to following, to not show notices and warnings.
error_reporting = E_ALL & ~E_NOTICE & ~E_WARNING
if you want do it by custom php.ini on the account, copy the main php.ini to user folder and edit that file.
cp /usr/local/lib/php.ini /home/$user/public_html/php.ini
and then edit that file, and change error_reporting