Hi @Tirunagari, Ramesh ,
the Azure classic administrator role will be retired today (31 August 2024). This was announced via email a lot of times in the past.
If your account is removed from the RBAC admin role you need to contact another admin in your organization to add your account again to the RBAC role.
If there is no other admin your best option might be to open a support case with Microsoft Azure support.
Azure Billing and Subscription support is offered by Microsoft by no cost and it's for free.
Source: Azure Support plans
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Regards
Andreas Baumgarten