You can do this by removing {if $modulechangepassword}<li id="tab2nav"><a href="#tab2" data-toggle="tab">{$LANG.serverchangepassword}</a></li>{/if} from the clientareaproductdetails.tpl located in your default template files. Keep in mind removing this line will also remove it for shared hosting and other products. Possibly you could put in another syntax that says if product=x then don't show this if you only want it to be excluded on VPS Module.