I94 question

I have two I94 cards, one is for F1 status, with an admission stamp. The other I94 is for H1 status, I got it on the same page as my H1B approval (because I transferred by status from F1 to H1 in US).

Now I plan to travel back to China, which I94 should I return to the airline when I depart US?

Do I have to return the H1B i-94? I hate to detach it from the approval notice and also, that i-94 doesn't have an admission stamp at all.

Thank you. Please share your experience and that would be much appreciated!