How do you removal the invisible walls on both sides of the human cemetery in levels 1 and 4?

Level 7 it's already accessible because the invisible wall isn't there

Remove the respective "Fence" chunks from the terra file(s).
You can use Lucas' Map Data Viewer to view chunks by their index & delete the ones you want to get rid of.

Ok so I opened L1_TERRA.p3d with that Map Data Viewer app. If I got it right, the invisible wall (or fence) in the North Entrance of the Human Cemetery is "Chunk Index 2610" and the invisible fence in the South Entrance of the Human Cemetery is "Chunk Index 2612".

I've deleted both of their "Wall Collision Container" tabs, then re-opened L1_TERRA.p3d with the app and it shows both entrance's fence have gone. But then playing the game the fence is still there as I can't drive through it unless I up the car's Mass by a few digits

What did I do wrong?

Thanks

I am not really sure, if you could send me that file, that would help. I am not home now, but I will check it once am.

Ok well I don't know if I need to send it to you but I can let you know what to do from your own copy, go to The Simpsons Hit & Run main folder>art>L1_TERRA.p3d

You can either edit that or edit a copy inside a Mod file

Never mind I figured it out! You also have to delete the gate chain fence thingy in l1r7. Now you drive through it like it's air