Users can chat with each other inside the Google Docs, Sheets, and Slides files they are working on together with classic Hangouts.
G Suite administrators can turn off chat inside Docs, Sheets, and Slides by turning off classic Hangouts. See Turn classic Hangouts on or off for users.
Note: The classic Hangouts service is not available in G Suite Essentials edition. Chat is always turned off in Docs editors if you have a G Suite Essentials account.
Conditions that automatically turn off chat
Chat in Docs, Sheets, and Slides is automatically turned off for your users according to the applicable age in your country. Also, some chat history and sharing settings automatically disable chat in Docs, Sheets, and Slides. For example, chat is disabled when you: