How do I stop being asked for a code when I sign in?

Turn two-factor off. Sign in, click your name or picture at the top right (on a narrow screen, the menu button), then My Account. On the My profile page, find the Two-Factor Authentication card and click Disable Two-Factor. Type your password, then click Turn off. Signing in then asks for your password only, and Panoramr emails you that two-factor was turned off. An account made with Google, Facebook or Microsoft has no password until you choose one under Update Password, so do that first.

There is no "remember this device" choice: while two-factor is on, the code is asked for at every sign-in, also after Google, Facebook or Microsoft sign-in.

If you are signed out and have lost your phone, click Use a recovery code on the code page and type one of your eight recovery codes. If you have neither, there is no way to reset two-factor yourself, and resetting your password does not turn it off. Write to moc.rmaronap@tcatnoc from the address on the account. Set up two-factor authentication has the rest.