How to change a specified code in a specified template with a specified code

[al3bed]

I already know how to change the value of an existing variable, I want to modify the template in a plugin

for example I need to render newpost_quote template as empty of it's content for specific users using a plugin. it's mean without needing to update the template manually. code to replaced and rendered whenever the specific users come into that place

PHP Code:

$coco = vB_Template::create('newpost_quote')->render();
$coco = str_replace($coco, "", $coco); 


now, what I suppose to do to make $coco work?