Old School Runescape

I'm trying to clean up old accounts i don't use anymore and that includes Runescape, which i have not played in years. I have found their support page but it's useless.

I can log into my account through the OSRS site (but not the new school Runescape site) but none of the settings i can find there seem useful. I don't have a Jagex account, and i'm not sure that would help anyway. Especially since i'm trying to have fewer useless accounts, not more. Trying to submit a request to delete my data on support.runescape.com, i'm asked to log in to do anything. The provided login link doesn't do anything, it just takes me back to the main support page. I also don't see any email address i can try. It's all just broken support forms. The Jagex support site just has links to support sites for specific games rather than any support.

So what's going on here? Is there anything i can do about this? Is there some secret hidden button on the RS settings page where all the useful options are hiding? I know the team is small and busy, but surely there's some solution to this.