We are currently running Jom Classifieds on Joomla 2.5. I have set comments to none and uninstalled comments but a comment button still appears on the advert. how do I hide this button as I do not want it displayed on the site

You should disable the comments in Jom Classifieds General Configuration and clear your cache and check. If still you have issues, kindly provide your site URL and the Joomla admin username and password. So that we can check and update you.

Thanks.