LG C3300 User Manual page 122

Make sure the power is off before you remove the battery.
Press down on the rear cover in indicated position and slide
downwards to remove, prize the battery by inserting finger nail in
to indicated slots and levering the battery out.
n
Removing the battery from the phone when the power is on
may cause the phone to malfunction.
Hold the top edge of the battery and lift the battery from the
battery compartment.
C3300 User Guide