Car Rental Express rentals generally cannot be one-way rentals. CRX affiliates are independent car rental agencies. Returning the rental car to other than the renting city is in most instances not possible.
Here is how you can check for one-way rentals: if you are travelling cross-country, choose a mid-tier or franchise agency in your Pick-up city or airport (an agency like Payless or Advantage). After selecting a vehicle, you will see an email Inquiry button lower on the rental page, where you can contact the Agency directly to ask about one-way rentals to other cities that they serve.
If you are staying in the region or in the same state, many agencies may offer one-way rentals. Send them an Inquiry, as above.