[ It won’t !
There is NO time to hold an impeachment trial, let alone the actual trial in the Senate. ]
In an ideal world the Joint chief of staff would have him placed under house arrest for mental instability and start removing his from his role as: “Commander in Chief of the military”
He could still be the “head of the civilian government as President” for the rest of his term, but his military power would be stripped down and given to Biden..... (shudder)....
We don’t live in that kind of a world.
as commander in chief, can he be charged with court marshal?
Hand picked Joint Chief. The system does have its flaws.