I assume you mean the plastic liner tube, typical would be the hollow plastic cone is mated to the adjustable cup.

The cone spreads the tube, often causing an interference fit- needle nose pliers strategically worked at the liner at the chain stay with sometimes an initial assist of a very small "minus" ( flat) screwdriver can allow grabbing the liner and twisting it out on a counterclockwise move.

way back these often failed at this point as the plastic got brittle over time. New are around... I just bought two from velomine fit $22 ea. not cheap for plastic but the frame has a cutout bottom bracket and it should be Campagnolo true..