Welcome to the Microsoft Q&A forum.
Based on the error described above, a support request will be required to delete the Public IP address. VCould you please send an email to azcommunity@microsoft.com with the below details so that I can create a one-time free support request for you in this case.
Subject : Attn Chaitanya
Thread URL: Link to this thread.
Subscription ID
Please let me know once you have done the same.
--
Please "Accept the answer" if the information helped you. This will help us and others in the community as well.