I would assume no. The invisible walls in games are meant to be there to prevent players from reaching areas, to do this is to mess with the game itself, thus resaulting in a completely different game you would be playing.

Is it possible to eliminate invisible walls in game without using cheat codes?

If yes, then yes.

If no, then no.

Depends on the game but since its a cheat code im sure that its not going to happen

What exactly do you mean by "fix"? Is there something in the game itself that lets you do it, or are you modifying the game data? If you're modifying game data then that's a strong "hell no", and would almost certainly be considered cheating.

In any case, you're better off discussing this with the community of whatever game this is for.

My point was if disabling something is possible in the game without the use of obvious cheat codes or external methods, then it should be fair game.

Try asking the SM64 forum then.