If you haven't e-filed your return then you can go back and correct your routing number. Please see Where do I enter my bank's routing or account number?
If your return was accepted by the IRS then it is too late to make changes. You can call the IRS to stop the direct deposit if your return hasn't been posted to their system yet. For security reasons, the IRS can't reroute your refund to a different account, so you’ll get your refund via a paper check. Please see What if I entered the wrong bank account for direct deposit?