If you search the internet for an article related to reset Azure Multi-Factor Authentication (MFA) you would most probably come across the old method, but a new CMD is available in MSOnline PowerShell module which can be utilized to reset the MFA.
NOTE: You need Global Admin rights to run this CMD.
If you do not see this cmd in your PowerShell session make sure to update your module by running the following CMD (need local admin rights)
and then the following CMD can be run.
Reset-MsolStrongAuthenticationMethodByUpn -UserPrincipalName firstname.lastname@example.org
If you are still using the old method I hope this will help you to quickly reset the MFA for users.