The Austrian first became a shareholder in Williams in 2009 but has been slowly reducing his links since the start of his involvement with Mercedes in 2013.
Wolff's shares, a little under 5%, have been bought by US businessman Brad Hollinger, whose stake rises to 15%.
Healthcare entrepreneur Hollinger first bought into the team in 2014 but has no formal management role at this stage.
However, he said that he would be "happy to participate in any way they see fit".
And Williams chief executive officer Mike O'Driscoll said the team "would be delighted if he could make a greater contribution to our business in the future".
Wolff, who agreed with Mercedes when he became its F1 boss that he would work towards ending his involvement with Williams, said: "I am surprised how emotional I am about this day, to be cutting my final business ties to [team founder] Sir Frank Williams and to the team at Williams.
"Having entered the team from a pure investment perspective, I soon found myself in a much more active role, helping to restructure this great independent F1 team.
"I am proud to have joined the sport with a team of true passionate racers, where we had to make spot-on decisions for the future of the business and its employees; I learned some lessons the hard way, but they were all valuable for understanding the industry."
Sir Frank Williams remains the majority shareholder in his team with 52% of the stock; his co-founder Sir Patrick Head holds about 9%, with just under 21% listed on the Frankfurt Stock Exchange and 4% held by an employee trust.
Wolff added: "I look back with pride on the first ever IPO (initial public offering) of an F1 team in Frankfurt, and can see the next generation of the Williams family leading the team into a bright future."
Sir Frank Williams said: "Given his role at Mercedes-Benz, a full divestment in Toto's shareholding became inevitable and we thank him for this judiciousness in only selling to a suitable buyer when the time was right.
"In Brad Hollinger, Toto has sold his full shareholding to a highly successful businessman with an immense passion for Formula 1 and our team - he is a great asset."
Mercedes Formula 1 boss Toto Wolff has sold off his remaining shareholding in the Williams team.