Once one of the two big party Presidential candidates gets elected, and our worst fears about them become confirmed, do you think there is a clear practical way to remove them from the WH, or are we stuck with them for 4 years?

Based on the 25th Amendment to the Constitution, there is a way, though barely clear, and in these times, even less practical.

The House of Reps can impeach a President for designated high crimes, as 2 Presidents have been; and then the Senate can exercise power to remove them from office with a two-thirds vote. This has never happened. 

Given that this process will be dragged on ad nauseum --possibly for years--at the expense of getting precious little of The People's other business done, and the present Congress can't squeeze out a two-thirds vote on what day it is, we can question what practicality really exists. Fair to say we're stuck with our mistake, for an uncomfortably long while, unless some nut goes all "Grassy Knoll". 

If it isn't already self-evident, despite Jefferson's proclamation, "We the People" really have very little input as to the way our country is governed, and not much more as to who does the governing.

(Putting soapbox away now) 

Toxic hairball where u been im running for president. So vote for otis. Ancient hippy will be vice pres. Rooster is secretary of air force. I will have a job for u

They can be impeached.

Why not look at the third party candidates? If all the people who don't want Hillary or Trump would actually vote for neither, than neither would win.