Those alumni say they're specifically protesting Jerry Falwell Jr.'s support of Trump's comments about the violence in Charlottesville, Virginia.
After members of the so-called alt-right, KKK and neo-Nazis clashed with counter-protesters, Trump said several sides deserved blame.
"We condemn in the strongest possible terms this egregious display of hatred, bigotry and violence on many sides, on many sides," Trump said shortly after the violence.
Two days later, Trump condemned neo-Nazis, white supremacists and the KKK by name, calling them hate groups.
But a day after that, Trump again said Charlottesville was an issue with multiple sides.
"You had a group on one side that was bad, and you had a group on the other side that was also very violent," Trump said.
Falwell tweeted he was proud of Trump's "bold truthful [statements] about Charlottesville."
And in a Sunday interview with ABC, Falwell reiterated that support, saying he agreed with Trump's statement that there were "very fine people on both sides" in Charlottesville.
The alumni group hopes "revoking all support" will send a message to the board of trustees that Falwell is unfit to lead the university.
The group says it plans to return diplomas to Falwell's office by Sept. 5.