Trump claimed that he graduated top of his class and criticized Obama’s grades, but never provided college transcripts. His lawyer Michael Cohen threatened schools on his behalf not to release any information on his grades.

William T. Kelley, professor of Marketing at Wharton School of Business and Finance at the University of Pennsylvania, said over the course of decades that Trump was the dumbest student he ever had.

Frank DiPrima, to whom Kelly said this to repeatedly, recounted:

Professor Kelley told me 100 times over three decades that “Donald Trump was the dumbest goddam student I ever had.”  I remember his emphasis and inflection — it went like this — “Donald Trump was the dumbest goddam student I ever had.”  Dr. Kelley told me this after Trump had become a celebrity but long before he was considered a political figure.  Dr. Kelley often referred to Trump’s arrogance when he told of this — that Trump came to Wharton thinking he already knew everything.

Time – Donald Trump Criticized Obama’s Grades. But His Lawyer Threatened Trump’s Alma Maters Not to Release His Own Grades
DailyKos – Former Wharton Professor: “Donald Trump Was the Dumbest Goddam Student I Ever Had.”
Study International – Revealed: Trump’s professor thought he was his ‘dumbest student’ ever