@s.karpe   if you or others need to know the answer to this what you have to do is create the user in your normal method then back to the user record form or list ensuring the 'Managed Domain' & Domain fields/columns are on show and set 'managed Domain' from 'false' to 'True'.  Now you can change the  domain to 'global' or whatever you want. 

Don't change back to 'False' though as the domain will revert back to what is was before