In the United States, the concept of a working class is only vaguely defined but economists and pollsters generally regard “working class” adults as those lacking a college degree, rather than by their occupation or income, see Wikipedia.
Since Donald Trump took an economist degree and was the founder of Trump University, calling him working class is ridiculous.
Meanwhile, sociologists in the US define the class system a little differently.
Sociologists Dennis Gilbert, William Thompson, Joseph Hickey, and James Henslin have proposed class systems with six distinct social classes. These class models feature an upper or capitalist class consisting of the rich and powerful, an upper middle class consisting of highly educated and affluent professionals, a middle class consisting of college-educated individuals employed in white-collar industries, a lower middle class composed of semi-professionals with typically some college education, a working class constituted by clerical and blue collar workers whose work is highly routinized, and a lower class divided between the working poor and the unemployed underclass. link
Either way, Trump isn't working class by any stretch of the imagination.