[Publius]

Federal workers unions exist due to a JFK EO. In theory another EO can cancel it.

Congress codified Kennedy's executive order into law in 1965, and President Johnson signed it.

[T Ruth]

Congress codified Kennedy's executive order into law in 1965, and President Johnson signed it.

Can you give a cite to the U.S. Code for this?
According to Wikipedia (which could always be wrong):

Executive Order 10988 is a United States presidential executive order issued by President John F. Kennedy on January 17, 1962 that recognized the right of federal employees to collective bargaining.

Passage of the executive order forestalled the legislative Rhodes-Johnson Union Recognition bill ...

Executive Order 10988 was effectively replaced by President Richard Nixon's Executive Order 11491 in 1969.

Some have proposed repeal of Executive Order 10988, which could potentially occur if the President were to issue an executive order vacating Executive Order 10988.

[Reily]

Thanks ! Did not know that!
So now that’s hard too. It still needs to be done !