Disable Snapchat My AI from Chat feed is pretty simple, All you have to need is a Snpahcta premium or snapchat plus subscription to execute the method - 

1. Open the Snapchat and go to the "Chat" section.

2. Tap and long press on the "My Ai" Chat.

3. Select the "Chat Settings" from the appear options.

4. Then, Choose "Clear from Chat Feed" option

A popup will appear on your screen to confirm your decision. Tap on the "Clear" option.