docs: added info about how to remove nix from dev setup.

docs/contributing/dev-setup.rst

@@ -34,6 +34,13 b' following commands:'
 
    Update your channels frequently by running ``nix-channel --update``.
 
+.. note::
+
+   To uninstall nix run the following:
+
+    remove the . "$HOME/.nix-profile/etc/profile.d/nix.sh" line in your ~/.profile or ~/.bash_profile
+    rm -rf $HOME/{.nix-channels,.nix-defexpr,.nix-profile,.config/nixpkgs}
+    sudo rm -rf /nix
 
 Switch nix to the latest STABLE channel
 ---------------------------------------