Smart Compose is a Gmail feature that began rolling out in the Fall of 2018. It shows suggested replies when available. Smart Reply is automatically enabled in the new upgrade. 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.