No, deleting entries in the registry will not clear a password. As mentioned is this FAQ entry, the password hash is stored in the registry in a hashed format. Deleting the hash from the registry will not remove the password itself, but will simply remove the ability to authenticate with that password.
If you need to clear a password, the correct way to do so is to use the built-in Windows tools to reset the password or remove it entirely. For example, if you have administrative access to the computer, you can use the Local Users and Groups snap-in or the net user command to reset a user’s password or remove it entirely. If you don’t have administrative access, you will need to contact the system administrator or use a password reset tool designed for that purpose.