ok guys trying to change the gas lines on my 1990 blazer 2dr have most of the lines out problem is trying to get the lines out towards the front how do i remove the plastic locking thingy that is right behind the driver front tire were the lines come out the frame to the engine

 

if you can post a picture. all those things are different on all sorts of cars, some you have to push the plastic, some you have to pull, others you need a tool