You can use any internet browser and log into www.icloud.com/find without needing a two-factor code.
You can also log into www.icloud.com (without the /find) and ignore the 2-factor code window and click the Quick Access to Find My icon that will appear and you will not need a code.
You cannot turn off two-factor authentication if it has been on for 2 weeks or longer. See the following from Two-factor authentication for Apple ID - Apple Support
If you already use two-factor authentication, you can no longer turn it off. Certain features in the latest versions of iOS and macOS require this extra level of security, which is designed to protect your information. If you recently updated your account, you can unenroll within two weeks of enrollment. Just open your enrollment confirmation email and click the link to return to your previous security settings. Keep in mind, this makes your account less secure and means that you can't use features that require higher security.