Turn the computer over and open the display. You should see that the keyboard is loose.
Before attempting to remove the keyboard, note that a ribbon cable connects the keyboard to the logic board. Improper removal may damage your keyboard.
Slightly lift the front of the keyboard up, and slide the keyboard towards yourself.
Carefully lift the top half of the keyboard and pull it towards yourself.
Push the display screen back to give yourself enough space to remove the side panels.
Before removing the side panels, note that removing the side panels hastily will damage the underlying panel screw. However, this will not affect the functionality of your PowerBook.
Remove the panels on either side by gently but firmly pulling up on them with both hands.