Finally I find an alternative solution. Create a new user role and do not grant any permission. After user login Plesk panel, user can change their own password by click profile tab and change the password. I tried and it works.
Yes, I meet same problem. I want to create a user role which only give them permission to manage their own mail accounts, but failed. Only one option related to mailbox, that is "Create and manage mail accounts". If I selected one, then this user role could manage everyone's mail accounts...