Acton, who sold his company to Facebook for $19 billion, criticized Mark Zuckerberg of abusing users' privacy by allowing ads on Facebook.This isn't the first time Acton has called on people to disengage from Facebook. Last year, he showed support on Twitter for a

#DeleteFacebook social media campaign triggered by the data privacy scandal started when news broke Cambridge Analytica, the political marketing firm linked to the Trump campaign, had inappropriately obtained the private information of 87 million Facebook users.

"It is time. #deletefacebook," Brian Acton said in a tweet, using the hashtag protesting the handling of the crisis.

Acton is now the head of non-profit Signal, a rival messaging app that focuses on security and privacy.

He and his cofounder, Jan Koum, sold to Facebook in 2014 and in his talk at Stanford Acton defended his decision to sell.

"I had 50 employees, and I had to think about them and the money they would make from this sale," he said. "I had to think about our investors and I had to think about my minority stake. I didn't have the full clout to say no if I wanted to."