Did you give AteMate a test run to get a feel for it, or are you coming back after some time away? Either way, you can start a new path.
Reminder: this will erase all previous meals from your path, and you will not be able to access them again.
You will also need your account details (email and password) to restart a path.
When you are ready to erase everything previously added to your timeline and start fresh, go to Profile > Settings > Reset path > type in your password to confirm you understand everything will be cleared > Reset. (You can also reset your path using Sign in with Apple.)