You would need to pull the carpet up to find the top of the clips, remove a little sealant from it, and then squeeze the metal tabs together with a pair of pliers.
Installation is the reverse except you must spread the tabs.
No, mine were in good shape. I was replacing the fuel line. After I figured out how they worked, it was easy. I took an old wood chisel and pryed apart the two wings of the clip from underneath. No carpet removal necessary.