Minimum password length
Computer Configuration\Windows Settings\Security Settings\Account Policies\Password Policy
Description
Determines the least number of characters a user account's password may contain. You can set values between 1 and 14 characters, or you can establish that no password is required by setting the number of characters to 0.
By default, this setting is defined in the Default Domain Group Policy object (GPO) and in the local security policy of workstations and servers with a value of 0.