Recently I had to enable and disable FTP many times during some testing I was doing. It's very easy to do, I done it via the command line as I could just up arrow through old commands and did not have to keep typing it in or click on boxes etc.
You could always save the commands to a script or create an alias so you just have to type enable_ftp for example.
To enable FTP, in terminal type
sudo -s launchctl load -w /System/Library/LaunchDaemons/ftp.plist
To disable FTP, type
sudo -s launchctl unload -w /System/Library/LaunchDaemons/ftp.plist
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