Would deleting an account on site affect forum integration?

[tahbikat]

Pretty much the title. :P

If I were to delete a few accounts on my main site because, say, a user has made too many accounts which is against the rules, would it have an effect on member forum integration in any way?

Alternatively, could I just ban the accounts? Would that ban every associated IP Address/email or just the one account that was banned?

Thanks ^^