Hide Simple products but still show navigation in left hand menu

[onecreations]

Hello,

We are looking to hide simple products from being visible in the front end. However, we do not want it to hide the left hand navigation. Is this achievable? 

The site is - http://magento2.onecreations.co.uk/coolrocks.co.uk/index.php/ladies-wedding-rings/style/diamond-ring...

It has a customized detail page - http://magento2.onecreations.co.uk/coolrocks.co.uk/index.php/ladies-wedding-rings/style/diamond-ring...

Any help will be appreciated.

Regards,

Andrew