USAID as the specific agency was established by executive order, in response to legislation (the Foreign Assistance Act) passed by Congress requiring such an agency to exist, and other legislation that continues to fund its operation.
If the goal is reorganization then it could be argued that the president has the power to do so provided it still meets the requirements of the legislation passed by Congress.
If the goal is to simply delete the agency with no replacement and let the funding stop indefinitely, that is not so clearly within the president's power and has precedent against it.
If the goal is reorganization then it could be argued that the president has the power to do so provided it still meets the requirements of the legislation passed by Congress.
If the goal is to simply delete the agency with no replacement and let the funding stop indefinitely, that is not so clearly within the president's power and has precedent against it.