What is "sign off"?
Native speaker’s answer
Rebecca
The phrasal verb "sign off" here is being used to mean conclude something. Usually it is used when talking about a letter, broadcast, or other message. As said here in the clip it was a "final message" to conclude the end of the "Whole Earth Catalogue". Ex: I will sign off here. Have a great day everyone. Ex: He always signs off his emails like that. Ex: Yesterday the news announcer signed off with a warning.