To remove the battery, flip the laptop over, loosen the screws on the base cover, and gently pry it off using a plastic scribe. Lift the cover away, locate the battery highlighted in blue, and unplug the battery cable. Then remove the screws securing the battery and lift it out.
To reinstall the battery, align it with the screw holes, secure it with the screws, and reconnect the battery cable. Snap the base cover back into place and tighten the screws to finish.