ONLY THE CONGRESS has the power to set immigration and naturalization policy...................
Kick them ALL OUT! Seize their assets to help defray the costs. OUT!
Congress gave the President some direct authority some time ago:
Whenever the President finds that the entry of any aliens or of any class of aliens into the United States would be detrimental to the interests of the United States, he may by proclamation, and for such period as he shall deem necessary, suspend the entry of all aliens or any class of aliens as immigrants or nonimmigrants, or impose on the entry of aliens any restrictions he may deem to be appropriate.
https://www.law.cornell.edu/uscode/text/8/1182
The "travel ban" is such an exercise of this power, which is why the court cases and their bans are such an outrage.