COROLLA corner lamp disassemble

Hi all,

I have trouble to disassemble my 2000 Corolla Passenger side corner
lamp(part#8151002040), there is something at the bottom of lamp shaped
like wedge stuck at reception joint, even though I spray some WD-40,
still it cannot be disconnected. I try to disassemble it without
taking out headlight assembly, not sure whether disassemble headlight
compartment is required or not. thx