Smart Reply is a Gmail feature that shows suggested replies when available. It is turned on by default. Follow the steps given below to disableSmart Reply.
Open Gmail and click on theSettings(gear) icon>Settings.
Navigate to the section titledSmart Reply.
Toggle the radio button toSmart Reply off.
Scroll down to the bottom of the page andSave Changes.
Smart Reply will now be disabled. It can be turned on at any time.