That is all past. They can’t decertify them. It is entirely in the hands of the Congress as per the constitution. It doesn’t and cannot “go back to the states”.
Nor does the 25th amendment designed to handle incapacity (sickness or injury) while in office.
On the other hand since you seem to be for federal power at whatever the cost to our freedom.
Glad you have so much faith in the democrats convicting in an impeachment trial. They did it during Clinton, then they voted for Obamacare and on and on. So I guess you might be in for a real shock when they they deem him not guilty. AND THEY WILL! LOL!
Have a nice day.