NEW YORK — The 92-year-old media mogul Sumner M. Redstone planned to leave his former companion Manuela Herzer $50 million and his Beverly Park mansion in Los Angeles that is worth about $20 million, but that was before he removed her from his estate plan in October, according to court documents filed Tuesday by his lawyers.

Those assets now are designated to go to Redstone’s charitable foundation after his death, the documents show.

Redstone changed his estate plan on the same day he removed Herzer from an advance health care directive that would have put her in charge of his health decisions. In November, Herzer filed a lawsuit, claiming that Redstone lacked the mental capacity to remove her from the health directive.

The legal dispute is personal, but the outcome of the lawsuit, including any finding about Redstone’s mental competence, could have implications for his controlling stake in Viacom and CBS.

Redstone’s lawyers have called the lawsuit meritless and have said that Herzer, a former romantic partner, was after his money.

“This is a pre-death trust contest dressed up as health care litigation,’’ lawyers for Redstone stated in the documents filed Tuesday.

Redstone’s daughter, Shari, revealed in a court filing last week that Herzer had received more than $70 million in cash and assets from him since 2009.

Pierce O’Donnell, Herzer’s lawyer, said in a statement that his client’s sole concern was Redstone’s well-being.

“The only reason Manuela is fighting this fight is out of concern for Sumner’s well-being and a desire to honor the decisions he made when he was competent to do so,’’ he said.

“The fact is that she is one of the only people around Sumner who has consistently put his interests first, which is why they regard her as such a thorn in their side,’’ O’Donnell added.

Last week, Redstone resigned as executive chairman of Viacom and CBS after investors and analysts raised questions about corporate governance issues at the companies, prompted by Herzer’s lawsuit.

As part of the case, a California judge had ordered Redstone to undergo a medical examination, which occurred late last month, according to a person with knowledge of the event. Herzer’s lawyers are expected to file a new round of documents next week, and a hearing on a motion to dismiss is scheduled for Feb. 29.