How do I set up automatic credit card payment with Citibank when I don't have bank account with Citi?

3 ways to manage this

1) Set up GIRO with another bank account so that payment will be made on time

2) Pay manually via internet banking. But do not forget

3) Pay via AXS. But do not forget as well.

The viable option is to setup an interbank GIRO using other bank accounts. Depending on the bank you are using, you should be able to do it via iBanking or directly at the branch.