O FAQ do DS-160 diz o que fazer (com ênfase adicionada):
I am required to give the name of a contact or organization and a phone number, but I am not visiting anyone in the U.S.
If you do not know anyone personally you may give the name of the hotel, company or organization you intend to visit. If the question does not apply in your case, you may simply state “does not apply”. If you are in transit to a non-U.S. destination, please write “Transit”.
Are all fields on the DS-160 mandatory?
Most fields are mandatory and must be completed. The form will not allow you to submit an application with mandatory fields that are left blank. You will receive an error message and will be required to complete the field before continuing. The fields marked “optional” may be may be left blank, and the fields that give the option to select “Does not Apply” may be ticked if the information does not apply to you.