If you want to create an Apple ID without credit card, you’ll have to click on any FREE APP, and when prompts you to enter your Apple ID, you choose CREATE APPLE ID. When creating the Apple ID doing this, the option in payment info “NONE”may be available.
Ps: YOU’LL ONLY BE ABLE TO SEE THIS OPTION IF CREATING THE APPLE ID BY CLICKING ON A FREE APP AND CHOOSING “CREATE APPLE ID”. YOU CAN’T TURN YOUR EXISTING ACCOUNT ON A FREE ACCOUNT, YOU’LL HAVE TO CREATE A NEW ONE, USING ANOTHER EMAIL ADDRESS.
If you want to use your actual email address to create an Apple ID without credit card, you can go to http://appleid.apple.com change your primary address to another that you don’t use, but you have to verify this other email, so you gotta have access to it. After verified the other email address, the email that you are actually using as an Apple ID is free to use on an iTunes Store account without credit card