He's not "trying to undo" it. He's largely already undone it.
He has done permanent and irreversable damage to our relationships with our allies around the world. Countries like Denmark and Canada now have to look at us as potential adversaries as we repeatedly threaten to use military force to annex their territories.
He has obliterated our ability to maintain strong political and economic ties. Sure, with every administration comes tweaks to various foreign and economic policies, but American policies in general have been considered stable and reliable over the long term. Countries now believe, and have every right to believe, anything the US says only has a shelf life of 4 years before the next administration comes in and flips the table on a whim, and that anything Trump says only has a shelf life of until he has a conversation with someone else and randomly changes his mind. Businesses and governments can't be expected to function under those conditions, and it is going to take us decades at best to show the rest of the world that Trump and MAGA were just short blips on the radar and that the US can once again be trusted in the long term. That's assuming we ever get that trust back.
Even domestically, how many collective centuries of experience has been purged from federal government operations as a result of Trump's mass firings? Even if these agencies were re-opened and fully re-staffed tomorrow, how long would it take them to wind things back up and get back up to full strength? If they're re-instated after the Trump administration, how much damage would be caused in the interim, and how many years or even decades will it take to fix it? How much data that these agencies relied on has already been permanently lost?
How many years of scientific research has already been destroyed as time-sensitive experiments and studies get cancelled due to de-funding? Again, even if these institutions would be able to restart work tomorrow, how many experiments have already been invalidated in the interim? How many years are we now going to be behind in scientific research?
Same goes with vaccinations. Environmental damage. Race relations. The list goes on and on and on. What he has already destroyed in four months will likely take four decades to repair.
