WordPress will always redirect to the canonical URL of the content if you try to access a page not with its canonical url. If you installed wordpress without using a www then wordpress will assume that the root url for the install is without www. Or in other words, wordpress is not actively removing www, it is just a by-product of eliminating possibility of duplicate content.
As for whether you should use www or not, frankly this is the first time in the last 15 years I have heard of anyone that do not treat them the same….. but if he is responsible for your pay check, you can just change the “site url” and “home url” options in the general setting to have www and probably nothing more than that.