Changing your method
You can only have one method active at a time. You can't use SMS and an authenticator app together. Go to Settings → Security, choose the new method, and confirm it with a code: once confirmed, it automatically replaces the previous one. Your current method stays active until you confirm the new one. If you stop partway, nothing changes.
Turning off 2FA
If it isn't required by your organization, you can turn it off anytime from Settings → Security by confirming with a code. You won't be logged out.
Managing your recognized devices
Recognized devices are ones where you've already completed 2FA and chosen to be remembered, so you're not asked for a code every time. From Settings → Security you can see the list and remove any device at any time:
Removing the device you're currently using logs you out immediately.
Removing a different device leaves it connected: it'll just be asked for 2FA again next time it's used.
