When you register your number with any Tech Provider to get started with WhatsApp Business API, It is mandatory for to Enable 2 Step verification.
In order to Migrate to different Tech Provider it is important to disable 2 Step verification first.
Login to your Facebook Business Manager with Admin Account.
In case you have multiple Business Manager Accounts,chances are you may land onto some other Business manager page.
In that case, From the Left menu profile > Select your Business Manager (in which you current whatsapp number is integrated) > Click on it
This will Redirect you to Correct page.
Click on Phone numbers > Confirm the phone number > Click on Settings
From the Left Menu opt for Two Step verification and Disable 2 Step Verification
Once disabled you will receive an email on your registered email to further disable is for whatsapp.
The link will redirect you to a page on Whatsapp
Once you have successfully Disabled 2 Step verification , you will receive an notification