Yes it can be dome, I did it as well.
Go to ACP, then Look & Feel, there you choose your skin and Manage templates & CSS.
In skin_global edit showloginform, find string 'checked="checked"' and delete it!
That's it, Remember me is ticked off forever :sorcerer:
I think there's absolutely no support and on each support ticket and absolute bloat reply is generated. Never ever in the history we're using IPB we received a relevant answer from supprt. Most of the time we received "your forum is too old and not supported anymore" and were forced to do the upgrade to latest. And now if we want to do the uprage again, support is with no help at all saying "Unfortunately we are unable to support test or development sites via the ticket support system. If this issue occurs on your live site we are happy to investigate further, however we're unable to assist you with this issue at this time."
Great answer indeed, is there anybody else who's such a fool who will break down his live site trying upgrade from a very old IPB to the latest 3.4.6??