Users' data are the lifeblood of Facebook, and if they wanted to opt out of all of the platform's data-driven advertising, they would have to pay for it, Sheryl Sandberg, the company's chief operating officer, told NBC News on Thursday.

In an interview with "Today" co-anchor Savannah Guthrie, Sandberg again acknowledged that the company mishandled the breach that allowed Cambridge Analytica, the data analysis firm that worked with Donald Trump's 2016 presidential campaign, to harvest millions of users' information.

More of the interview will air Friday morning on "Today."

"It is definitely the case in 2016 that we were behind and we didn't understand that kind of election interference," Sandberg said.

"We thought that the data had been deleted, and you're right, we should have checked," she said.

Sandberg detailed some of the steps Facebook is taking to let users opt out of sharing some but not all of their data, like choosing not to hear from specific advertisers.

Sandberg said Facebook doesn't sell or give away its users’ information, even though "our service depends on your data."

So "we don't have an opt-out at the highest level," she acknowledged. "That would be a paid product."

The interview was one of several Sandberg gave on Thursday explaining how the Cambridge Analytica breach took place and taking responsibility for the company's handling of users' data, which the company has said were "improperly shared."

"We were given assurances by them years ago that they deleted the data," she said of Cambridge Analytica on "PBS NewsHour." "We should've followed up. That's on us. We are trying to do a forensic audit to find out what they have."

In a separate interview with Bloomberg TV, Sandberg said the company was also "systematically looking at all the ways Facebook data is used."

"We are going to find other things," she warned.