How to remove battery from 1999 cadillace sedan deville

Disconnect negative terminal (black) first. Then disconnect positive terminal (red).

Then, use a 1/2" hex socket and extension and ratchet to unscrew the hold down bolt that holds the black plastic hold down piece on the bottom of the battery.

Remove any cross members that block the lifting of the battery out of the battery tray, by unscrewing any bolts that are located on the plate.