Basically, here is how it will work:

What if I want to disable my account but not delete it entirely?
That's where account deactivation would come in.

You would go to Settings -> Account and a button named "Deactivate Account" would be at the bottom, with a warning on top of the button like this: "This option will disable your account, but you can re-enable your account by logging in. If you want to delete your account, go here instead."

After you would click the button, it would ask for password confirmation. A confirmation of deactivation would be sent to your email if the password was correct. If it was wrong, that wouldn't happen.