Dear Srikanth Ravada,
Good day! Thank you for posting in Microsoft Community.
Based on your description, it seems that you cannot edit or delete the calculated column created in Microsoft List app, and the column not listed in list settings.
If my understanding is right, we've also done some tests on different tenants on our side, we can see the calculated column in list settings and we can modify the column from there as expected as shown below.
We'd recommend you change another browser to check the outcome, if the issue persists, please navigate to List settings > advanced settings > re-index list to check the outcome.
[Notice: Reindex might take up to 24 hours to take effect.]
If issue still remains after re-index and browser change, we're afraid this issue may need to check the backend environment of your tenant for further investigation.
As forum support, we do not have enough permission and resource to directly check the environment of your tenant.
In this situation, we sincerely recommend you contact your Microsoft 365 administrator, follow steps in this article and try to create a support ticket to contact Online Support. The support team over there has higher permission than us, they can remotely help check the situation on your side, involve more resource to collect logs and help you do troubleshoot. This would be a more efficient way in handling this case for you.
For reference: How do I find my Microsoft 365 admin?
Your understanding and patience will be highly appreciated.
Sincerely,
Rhoda | Microsoft Community Moderator