To stop it falling into a "very negative spiral" that he found "distressing" before his exit.
Paddy Lowe left Mercedes at the end of 2016 to join Williams as chief technical officer, as well as becoming a shareholder in the team where he worked between 1987 and 1993, winning the world title in 1992 with Nigel Mansell.
But Lowe's return to Williams proved less successful as the team slumped to the bottom of the constructors' championship in 2018. Significant delays in the construction and design of the 2019 car led to Lowe being placed on gardening leave before his ultimate departure three months later.
Williams has finished last in the constructors' championship in each of the past three seasons, but underwent a change in ownership last summer after the Williams family sold its shares to Dorilton Capital and left the team.
Speaking on the Beyond the Grid podcast, Lowe said that he felt "pleased" when he heard the team had been sold and that the Williams family would be leaving.
"That's what they've needed to do for a long time, and to be honest, should have done it earlier, for all sorts of reasons which are not to do with any individuals," Lowe said.
"The team has been in a very negative spiral from a funding point of view. While I was there, I was watching that spiral progress further down the drain, and it's actually quite distressing.
"You understand that there's no good end point apart from a sale. So you may as well cut that now and move on before it's all gone.
"I'm very happy that the team was sold for a reasonable price so that Claire and her brothers leave with something to work with from the great things the family has achieved over the years, and the name is kept.
"They've got new investors who will have the cash to take it forward and turn that spiral in the other direction, which will be a long process. People who are patient will take them there."
Lowe said during the podcast that his second stint with Williams was "a period I don't really like to dwell on" and that he "didn't enjoy" the time back at Grove, calling it "really hard work for no reward whatsoever."
Lowe felt that some of the issues at the team went further back than his arrival, believing the Mercedes power unit it used from the regulation change in 2014 onwards masked many of its issues.
"Williams had the benefit of the best engine by a long chalk from 2014, so that gave some, let's say, false impressions of underlying performance," Lowe said.
"They were living off a number of other legacy advantages that gradually unwind. When the organisation starts to lose its way because it hasn't had the right investment or made the right decisions, it doesn't instantly make bad cars. The unwinding is equally slow as the winding.
"I wish Williams all the best with their new owners. It's terrific they've got owners who have got funding, because in the end, you need funding for all of this."