How to remove your RuneScape account
Please follow the laborious instructions at the removal link. This (probably) goes for player accounts only. The RS site account may be different. Heck, why not ask at their support address to delete it? That is: accounthelp@jagex.com.
Direct removal link: https://services.runescape.com/m=rswiki/en/Account_removal
Helpful Trick: Removing online data
Publicly visible text/images often aren’t properly removed even when you succeed in removing an account. Try editing or removing them manually before removing the account itself. If you’re unsure what happens to your tracks: this can be found mostly in the Terms of Service/Privacy Policy; otherwise you can always contact RuneScape and ask personally. By the way, removal requests don’t necessarily mean your data will actually be removed (e.g. due to legal obligations).
Helpful Trick: Remove third-party logins
If you signed up for RuneScape using a third-party login such as Facebook or Twitter, you probably want to revoke all access from RuneScape. Click here to find out how.