On the File menu, click Save As.
On the Tools menu, click General Options.
In the Password to open or Password to modify box,
double-click the symbols that represent the existing password.
To change the password, type the new password, and then
Passwords are case sensitive. Type the password exactly as
you want users to enter it, including uppercase and lowercase
To remove the password, press the DELETE key, and then
If you changed the password, retype the new password, and
then click OK.