It takes a 2/3 majority of the Senate to remove a president from office. The Democrats are probably going to win the Senate, but they’re not going to flip 19 seats.
And if they somehow did, that would mean that the election is some kind of extreme, historic blowout that Trump has no chance of stealing no matter how much he cheats. You can’t pull a Bush 2000 if the map looks like Goldwater 1964.