The hashtag has been trending in the days since reports emerged that data analytics firm Cambridge Analytica accessed Facebook data without users' consent.
Users on Twitter had been urging Musk to delete his Facebook page, prompting him to tweet a response on Tuesday, saying, "What's Facebook?"
On Friday, another Twitter user nudged Musk to delete the SpaceX Facebook page as well. Musk replied, "Will do," after writing he "didn't realize" one existed.
Musk's official Facebook accounts no longer exists as of Friday.
A former Cambridge Analytica employee has accused the firm of mishandling the personal information of more than 50 million Facebook users in an effort to help now-President Donald Trump during his 2016 presidential campaign.
Facebook CEO Mark Zuckerberg responded to the allegations on Wednesday, acknowledging that the social media company "made mistakes" are is "working to understand exactly what happened" to ensure it doesn't occur again.
Cambridge Analytica has denied any wrongdoing, including allegations that it used or held onto Facebook data.