How many? I only think of one the Paris agreement that the US has withdrawn from. But that is not a legally binding treaty according to the US officials.

"United States officials to regard the Paris Agreement as an executive agreement rather than a legally binding treaty. This removed the requirement for the United States Congress to ratify the agreement.[13] In April 2016, the United States became a signatory to the Paris Agreement, and accepted it by executive order in September 2016"