got a 2k maxima all stock NO Bose

blew a rear speaker the other day so figured I would replace all the speakers.

First one I was doing was a front door.

pulled the speaker out....but how in the world do I make my new speaker fit? I cant figure out how to remove the oem from that plastic shroud or do I have to buy a new oem shroud or what?

any other surprises I need to be ready for?

Thanks in advance.

Greg