USAID was established by President John F. Kennedy with an Executive Order in November of 1961 in response to the Foreign Assistance Act passed by Congress in September of 1961 which mandated the creation of an agency to administer such aid.

The Foreign Affairs Reform and Restructuring Act of 1998 then established USAID as an agency within the Executive branch.

Section 413 of that law: “IN GENERAL.—Unless abolished pursuant to the reorganization plan submitted under section 601, and except as provided in section 412, there is within the executive branch of Government the United States Agency for International Development as an entity described in section 104 of title 5, United States Code.”

This language “there is within the executive branch” is the terminology Congress used to mandate agency existence. The part you see about abolishing it was a one-time option given to President Clinton to fold USAID into another body during a reorg if so desired. This option was not used for USAID, however he did elect to fold USIA into the State Department under this same authority.

USAID, by law, cannot be dissolved by Executive Order.

From the 2018 Congressional Research Service report titled “Congress’s Authority to Influence and Control Executive Branch Agencies“:

“The Constitution neither establishes administrative agencies nor explicitly prescribes the manner by which they may be created. Even so, the Supreme Court has generally recognized that Congress has broad constitutional authority over the establishment and shape of the federal bureaucracy.”