Arey bhai why is there so much ambiguity in answers!
Simply go to netbanking/mycards setup any pin for the new card using otp verification!
The existing card would be closed in a day or 2 or max 15 after activating new card!
No need to wait/txn etc.
Also credit cards have features like international transactions, online transactions, and contactless payments disabled by default when initially issued, meaning these types of transactions will not be allowed until the cardholder actively enables them through their bank's online portal(netbanking, mycards) or app(the HDFC APP)!
~ mark as solution iff it helped you!