President Donald Trump is sharply reducing the size of two national monuments in Utah. The move to shrink Bears Ears and Grand Staircase-Escalante national monuments by about 90% unravels protections established by former presidents for areas with unique archaeological and historical features.
national monuments can be created (and presumably uncreated) by a presidential declaration under the antiquities act.
Parks and forests require an act of congress and should require a similar act of legislation to undue that- but you’re asking if he can do that, and yes. That’s because neither congress nor courts want to.