To change your own password

1. Press Ctrl+Alt+Delete and choose Change a password.
2. Follow the instructions, tap or click Submit, and then tap or click OK.

To change other people's passwords

NOTE: To change passwords for other user accounts, you'll need an administrator account.

1. Swipe in from the right edge of the screen, tap Settings, and then tap Change PC settings. If you're using a mouse, point to the upper-right corner of the screen, move the mouse pointer down, click Settings, and then click Change PC settings.
2. Choose Users. Under Other users, tap or click Manage domain users.
3. In the User Accounts dialog box, select the person whose password you want to change, tap or click Reset Password, follow the instructions, and then tap or click OK.
4. Tap or click OK to close the User Accounts dialog box.

If you've forgotten your password and need to reset it Click the following link -  Resetting Passwords