To recover a lost SYSTEM account password, you will need to have access
to the system console.

From this point, you will need to get to the VAX or Alpha SRM dead-sergeant 
prompt (>>>).

(VAX) BOOT/R5:10000001 ddcu
(AXP) BOOT -FLAGS 0,1 [ddcu]

When you get to the SYSBOOT> prompt, type the following commands:

SET/STARTUP OPA0:
SET WINDOW_SYSTEM 0
SET WRITESYSPARAMS 0
CONTINUE

This will get you to an OpenVMS DCL prompt ($). Type the
following commands:

SET NOON
DEFINE/SYSTEM/EXEC DECW$IGNORE_WORKSTATION TRUE
SPAWN
@SYS$SYSTEM:STARTUP

This will run the OpenVMS startup sequence and return you to
the DCL prompt, where you should type the following commands:

SET DEFAULT SYS$SYSTEM
RUN AUTHORIZE
MODIFY SYSTEM/PASSWORD=new-password
EXIT
REBOOT

You should then be able to log in with the SYSTEM account and the newly
selected password.