Hello Bikash Kumar, when you create the azure subscription, you will get the default domain name in the format of example.onmicrosoft.com. You cannot change or delete this initial .onmicrosoft.com created for your tenant. In case you want a different name (say contoso.com), then, you can bring your custom domain to Azure and set it as the default domain. See this -- https://learn.microsoft.com/en-us/entra/identity/users/domains-manage#set-the-primary-domain-name-for-your-microsoft-entra-organization
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