Adding Code To Stop visual composer?

I saw in the FAQ that it is a good idea NOT to allow visual composer etc to be optimised. The following code is given:

—————
add_filter(‘autoptimize_filter_noptimize’,’pagebuilder_noptimize’,10,0);
function pagebuilder_noptimize() {
if (is_user_logged_in()) {
return true;
} else {
return false;
}
}
——————-

Please could you tell me where to put this code?

Thanks.