Q: When I go to the App Store I'm required to verify payment, on fre apps but my credit card is being denied. Why do I need a credit card and how can I avoid this?

If you did not create an Apple ID in the exact manner which is required for not using a credit card, you will have to enter a credit card now. That is simply how the process works. You can always remove the card after you get the cards verified. This is what you should have done.

Create an iTunes Store, App Store, or iBooks Store account without a credit card or other payment method

After the the card is verified, you should be able to remove it and then just use iTunes gift cards or download free content.

Change or remove your Apple ID payment information in the iTunes Store - Apple Support

You should take a look at this one too.

Pay an unpaid balance in the iTunes Store - Apple Support

MY credit card must have been verified because I used it but it ran out of money it was one of those mastercards gift card and obviously it is being denied and I can't remove it How can I remove it plz help

Did you follow these steps exactly as written here? If you did follow them, what happened when you tried this?

Use your iPhone, iPad, or iPod touch

1. Tap Settings > iTunes & App Store.
2. Tap your Apple ID, then tap View Apple ID. You might need to sign in.
   
3. Tap Payment Information. If you're using Family Sharing, only your family organizer can update the payment information.
4. Change or remove your information. To remove your payment method, select None. Get help if you don't see None or can't select it.
   
5. Tap Done.

If you change your payment method to a credit card, the iTunes Store places a temporary authorization hold on your credit card to verify your updated account information.