I'm not in a position to decide policy at this moment, so I'll just provide some of the background information.
If you are a model user, this pattern of account-creating doesn't cause many issues for moderators. More account numbers to keep track of, more scary warning messages to ignore, but that's about it. The only issue I can think of is other members ...
Stackexchange permits all users to maintain multiple accounts. It is if those accounts vote for each other or otherwise abuse the reputation system that moderators and/or staff will intervene.
It is also not compulsory to register an account. If you don't wish to register, you can participate as an unregistered user.
THe main benefit of registering and ...
If you wish to close your account completely, that can only be done by the SE staff.
This post is the explanation and it has a link to a contact form.
Complete the form and wait for the process to take its course.
Your profile will be removed from the system.
We'll be sorry to see you go.