How do I edit the rc.local file on my Raspberry using another PC?

I edited my rc.local file to start 2 python scripts and a flutter app on boot and I set it up to boot in console mode. But now I can't close the flutter app. I already tried pressing CTRL + Z or CTRL + C, basically all the possible key combinations and nothing happens.

Does somebody have a solution for this?

P.S. The flutter app is running using flutter-pi and the python scripts don't have any UI or something like that. They are used to execute functions when a button in the app is pressed.

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