Aftermarket deck install help on a 96 tacoma

Alright i bought a 96 toyota tacoma and the previous owner had an aftermarket deck put in which is a pos and i bought a new one and am having the hardest time figuring out how the plastic adaptor peice comes off. Ive installed a few decks and adaptor peices but i cant figure out how to get it out.

Can anyone help me?

thxbret