Auto-Delete Long Expired Members

Hi,

I need to implement an expiration period for one of our existing membership. Those expired members will need to be auto-deleted (member account & wordpress account). The reason is because, we do not want to bloat our database with those inactive members. Besides, they can re-register again anytime later with using same email address, if they wish to join us back after being deleted.
Please guide on how to perform the auto-deletion of expired members.
Even manual-deletion solution is highly appreciated.
Thank you.