Hi Niket,
If the subscription was created within the last 90 days you should be able to look through the Audit logs in the Azure Subscription.
Secondly, please see the following documentation to see if you can spot who may have created the subscription for Azure Portal:
Determine account billing administrator
The billing administrator is the person who has permission to manage billing for an account. They're authorized to access billing on the Azure portal and do various billing tasks like create subscriptions, view and pay invoices, or update payment methods.
To identify accounts for which you're a billing administrator, visit the Cost Management + Billing page in Azure portal. Then select All billing scopes from the left-hand pane. The subscriptions page shows all the subscriptions where you're a billing administrator.
If you're not sure who the account administrator is for a subscription, visit the Subscriptions page in Azure portal. Then select the subscription you want to check, and then look under Settings. Select Properties and the account administrator of the subscription is shown in the Account Admin box.
If this is helpful please accept answer.