The procedure used to erase the Battlezone high score table is similar to that of other atari games.
Put the game into selftest mode. Refer to your manual on where to locate theswitch. For uprights it is usually inside the coin door.
In selftest mode you should see a display that looks similar to this screen shot below.
Battlezone high score selftest display
While in selftest mode, press and hold both the "ERASED". This is the indication that the high scores have been cleared.and buttons. When both buttons have been pressed at same time, you should immediately see a message displayed on the screen with the text
Battlezone selftest showing scores erased
You can now release the buttons and exit selftest. The high score table will be returned to the factory default scores and initials.
Battlezone factory high scores