I removed the pipe recently in my build and once it is disconnected at both ends you swing it up and rotate it.
Eventually you will be able to pull it out of the opening in the firewall and into the engine compartment.
You do not go through the filler hole and nothing else secures it in place.
Mine was a little easier as I removed the return tube first since it was rotten.
This is what I was left with right after I removed it.
3 screws at the filler neck plus a ground strap to remove and remove the 90 degree rubber hose clamp at the other end.

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1986 Fiero2m8 (LT1 NX / 4T60 Roadster Build)
https://www.fiero.nl/forum/Forum2/HTML/071642.html