Hi Anurag,
I am sorry to hear that you are having trouble. We do not have a way to modify an existing card. However, we do have a delete endpoint.
This is a DELETE call to
/api/customer/cc/{ccid}
You will also need to supply your Authorization header, and your client_id as a parameter in the DELETE call.
In regards to the error you experienced:
What environment (full url) are you pointing the request to?
Can you supply any of the request payload?
Let me know and I will try to figure out what is going on for you.
Best,
Garth