Yes, you can pay your HDFC credit card through your reward points. But there is a twist. Not all types of credit card bills can be paid through reward points. 

The reward points that you have gathered can be availed as a cash back, which can then be converted as a cashback credit on your statement and it gets adjusted on your credit card bill. For this you need to have one of the "cashback" credit cards. You can't do this on all cards. There are a limited number of cashback cards like "HDFC moneyback credit card". To convert your points to cashback, all you need to do is login to your net banking and redeem it in a matter of a few clicks.

If you prefer using debit cards or credit cards for making regular and frequent transactions, you enjoy a host of benefits. Apart from greater ease of utility and convenience, one of the most popular advantages of using a card are the reward points. Reward points are points or credits accumulated in your name for specific frequency or volume of transactions. You can then redeem your reward points for online purchases or convert it into cashback to pay your credit card bill.

Additional Reading: HDFC Bank Credit Card Reward Points