Update Google 2FA Phone Number

If you need to update your Google Two-Factor Authentication phone number this requires manual update by the Google Account Owner.
After the Google Workspace Administrator has given you access to your account, you may navigate to your Google Account Settings and update/change your 2FA credentials. You may use the following direct link to get to your settings or navigate to these settings after successfully logging into your Gmail account.
https://myaccount.google.com/

From the Google Account main page, we will navigate to the security tab on the left, and then click the arrow within the 2-Step Verification line.

From this next page we can see our 2-Step Verification methods we have setup. If there is a phone number already setup it will show here, and by clicking on the arrow we can go to change that number. (It will make you input your Google Password again before changing this). 

After changing the number, Google will prompt you for verification by immediately sending a code to this new number, after successful verification you have updated/changed your google 2FA number.