You can edit or delete the post that contains the personal information on your own.
Besides that, What help are you expecting from a moderator regarding this matter?
You can reach out admin via PM if you want but I'd say they can't give you any help other than banning the user for sending threatening messages if you received via forum PM.
I think from the look of thing, ops won't be getting responds from any moderator because such case is an individual personal issue and only he can deal with it, making a post way back in 2013 that become a threat to him according to ops make the issue a personal things most expecially now that he said he gave being receiving life threatening calls that means he gave out a lot of information about his real life and the case is out of this forum, so for me, seeking help from forum moderators will be a useless approach and the best thing for him right now is to handle thing's based on individual capacity and should not involve moderators in personal business like this.
And still on still ops can stop hiding under a newbie account and make this request from his original account, that way he can easily get the needed help if his troubles eminated from this forum, because posting with his original account other than this alt will help prive the legitimacy of this claims, and also building the confidence and connection need to sort out the issue if he feels forum members are involved in the whole thing.