Only admin can delete the accounts but I don't think that admin has enough time to delete accounts of the users who create accounts and ask others that how to delete the account.
Correct. But OP can do both:
1. Contact the admins via PM to ask for account deletion, providing a reason. (Perhaps they will delete it, perhaps not).
2. Meanwhile, OP can forget about the account and continue with their life like bitcointalk doesn't exist.