We want to use one verification method to login for all users, by send otp by email only,Because most of the time we are not receiving otp through sms

Let me guide you on how you can verify your account using an email, Morssi.

The verification method provides extra protection against password theft. In QuickBooks Online (QBO), multi-factor authentication helps us protect your data, that's why this can't be turned off. However, if you want to use your email for authentication, we'll ask you to verify your identity when you sign in to your account on a device we don't recognize. You'll want to turn off the two-step verification method. 

1. Sign in to your Intuit Account.
2. Select Sign in & security.
3. Choose 2-step verification.
4. Turn off the Use 2-step verification switch.
5. Enter your account password, then Continue.

To give you more information about the security enhancements on top of the usual password when using multi-factor authentication, check out this article for more details: Verify Your Intuit Account With Multi-Factor Authentication Or Two-Step Verification.

Moreover, you may want to change or update some of the information in your Intuit Account, learn from this article for your future reference: Update Or Change Your Intuit Account Sign-In Information.

Please get back to us if you have any other concerns with the verification process when logging into your account. We're here to ensure everything is taken care of.