I was doing this to put weather stripping under there to stop the rattling from my sub
-First, remove the seat cushion. Then remove the shoulder cushion things.
-Then remove this thing on the C-Pillar using a flat head screwdriver to pry it out. It's easy.
-Then start pulling on the panel that says AirBag. Dont worry, the airbag wont deploy. And you get this
-There are 3 red clips and 1 white clip. The red clips are easy, just pull. The 1 white clip is the hard one to get out. It's the clip thats going to be closest to you. I ended up using pliers and using it for leverage against the weather stripping of the door. Be careful, I ended up bending the sheet metal where the white clip was connected to and the white clip didnt stay in when putting it back. I just used the pliers again, and bent it back.
This is what it looks like.
-Do the same to the other side.
-Go into the trunk and you'll see little white clips up top. Use pliers and squeeze them slightly and push up at the same time to release them.
-Now to remove the rear deck. Push up, or hit up with a mallet under the indentations you see in the picture.
-Lift up and pull out rear deck
Thanks to Jstone624
Rear deck rattle - 8th Generation Honda Civic Forum
Unlike him, i did not buy new clips, my red ones were perfect, my white ones were chipped but still went back in.