No President has the power or the authority to end “gun-free zones” unless the gun free zones were established by an earlier executive order. That is something a new President can undo.
But no President has any power or authority to direct the actions of free citizens, whether we like the actions or dislike them. That’s what liberty means.
You don’t like “gun-free zones”? Then take it up with the school board, the county or city government, whoever it was that had the bright idea in the first place. Don’t be expecting or demanding that every local bad idea be undone by an out-of-control over weening, over-reaching outlaw President.
President Trump, as Commander in Chief, could end “gun free zones” on military bases on day one of his presidency.
It would be harder to get rid of the “gun free school zones” legislation, but with a Republican Congress, he could, and should do it.
That legislation never made any sense execept as a way to disarm the country.