Q: How do I create a child apple ID if I don't have a credit card?

Hello ManikOsiris,

The credit card is there to verify age as well as to comply with privacy protection laws. You can put your debit card back on after you have added the credit card and have everything set up for Family Sharing. The article below will explain further about why a credit card is need for Family Sharing. 

Family Sharing and Apple IDs for kids

http://support.apple.com/en-us/HT201084

Regards,

-Norm G.