How do I switch my card to Apple Pay and not Apple Cash ?

Sorry, your question does not really make sense.

Apple Cash is a type of payment method you can use with Apple Pay. It's like a digital debit card.

Apple Pay is a conduit to make payments using payment methods such as credit cards and debits cards, one of which can be Apple Cash.

You are free to not use Apple Cash if you do not want to.

If using an Apple Card the cash back rewards will be placed in the Apple Cash Card. You can then transfer it to your bank account, or use it to pay your balance on your Apple Card.