You can set the all the phones pasword all in GO from CUCM, if you wish to have same or different password for phones registered to UCM altogether.
Configure "Common Phone Profile" and enter desired password and assign to the phones directly, you can configure multiple profile with different password in each profile and have them assigned to the phones, if you wish to have few phones having different password and few something else then you can perform this way as well.
1) Go to Device >Device Settings> Common Phone Profile.
2) Configure Common Phone profile .
3) Assign this common phone profile to the phone.
3) Reset, it will reset all the phones who all having this profile.
there is parameter for "Local Phone Unlock Password" set it whatever you like to and assign phones at "" . That's it.