A Stale Account is one that was created, yet didn't get Verified after the provided grace period. A disclaimer banner is displayed on the home page for every Unverified User, informing them of this and gives the exact deadline of the end of the grace period.
We delete Stale Accounts to maximize the security of the private information of our Users.
Register a new account. Since no Verification forms were submitted, or were all canceled, no valuable information was lost. It's essentially the same as starting from scratch anyway.