There is simply no way, unless you have visual access to the other player's account.
You cannot it is virtually impossible they can only tell you
ask them!
No, that is against the rules.
Yes but only in the wilderness or on a pk world.
not unless there is a trash can
Accounts cannot be deleted, only banned.
RuneScape private servers, but sometimes they get deleted.
In someones player owned house with high level construction.
A few, but new ones are created and old ones deleted frequently
No; it's usually better to have your account deleted if you no longer want to use it.
you can go to the bottom of their page and click report abuse..state the problem and it will be deleted
A human dressed in pink. Now no longer available after the quest was deleted.