I prefer to delete my accounts when I’m done with them instead of just logging out indefinitely, but there doesn’t seem to be an option in the profile settings.
So, Mod, delete my account.
You can’t delete an account, and neither can the mods, if you think about it the reasons are obvious. 
We can delete accounts, but as a matter of policy we don’t. We don’t delete posts because doing so screws up the threads in which they are posted. There’s a way to delete the account and keep the posts, but that makes it so that your username isn’t searchable and your posts aren’t connected to each other, making them less useful.
If you’d just like to be prevented from posting here in the future, I can change your password and email address or ban you permanently.
Actually that’s not right you can hard delete an account but it involves deleting so much meat of a forum that it tends to leave it without structure particularly when long term posters are involved, so as I say you can’t it is not pragmatic, possible yes but so unlikely that pigs will fly.
You can’t perma ban anyone Carleas you should know that by now if they want to post they will find a way if they don’t likewise. The IP thing is not going to work. The fact that you think it is possible is naive. That said hell you go ahead and try one day you might be right…?