The Commander in Chief of the military, also known as the President, has the authority to fire at will, that is how it works in America for 250 years now.

Right, and everyone else has the right to an opinion on it. The point seemingly being made above is Trump's swingeing cuts seem to be driven more by ideology than administrative efficiency. Xi's dismissal of his top general (which seems to be equivalent to sacking the Secretary of Defense or the Chairman of the Joint Chiefs of staff) is perplexing due to the opacity, but it doesn't seem to be indicative of any bigger or broader trend.

Guess it works that way in China too...