It looks like you are trying to do this at the top-level of your drive. You realize that if you do this then you're disabling all security for your drive? You aren't supposed be able to easily write outside your home directory as then any process at all could read/write whatever it wants.
If it's a throwaway install then if you really want to do it then just disable System Integrity Protection by rebooting into recovery mode and running `csrutil disable` in a terminal. Then restart, open Terminal, and chmod the entire drive to have read/write access with `sudo chmod -R 777 /`.
Again, I completely do not recommend doing this as it's utterly stupid unless this is a VM or throwaway machine that you are just fooling around with.