sign off

Short definition from Wiktionary

Noun

1. 1
   Misspelling of signoff.
2. 2
   Alternative spelling of signoff.

Verb

1. 1
   To log off; to stop using a computer, radio, etc.; especially, to stop talking.
2. 2
   To cease broadcasting a radio or television signal, usually at the end of a broadcasting day.
3. 3
   to give one's official approval to something for which it is needed, especially by a signature.
4. 4
   To use a valediction, such as the end of a letter or broadcast.