PG&E said it expects to have some $5.5 billion in financing in place to help it with ongoing operations when it formally declares bankruptcy.
The San Francisco-based company has begun a search for a new CEO following Williams' departure, according to a statement issued Sunday.
Bloomberg reported Saturday that the utility, facing billions of dollars in wildfire liabilities, could notify staff of a potential bankruptcy filing as soon as Monday, citing sources familiar with the situation.
Pacific Gas and Electric said it plans to file petitions to reorganize under Chapter 11 of the U.S. Bankruptcy Code on or about January 29, 2019. The California Public Utilities Commission is considering breaking up the power company.
The utility said it would keep spending on system safety as it provides gas and electric "in an environment that continues to be challenged by climate change".
PG&E expects the Chapter 11 process will "support the orderly, fair and expeditious resolution of its potential liabilities resulting from the 2017 and 2018 Northern California wildfires".
John Simon, who served as PG&E's executive vice president and general counsel, will now be the utility's interim CEO until the board finds a permanent replacement and said the utility's "single most important responsibility" is safety.
The company was acting under a new state law requiring it to tell employees at least 15 days before a change of control in the company - including a bankruptcy filing.
The company has seen two-thirds of its market value wiped out since November's Camp Fire - the deadliest wildfire in California's history.
PG&E, which serves 15 million Californians - nearly 40% of the population of the state - warned then it could face "significant liability" beyond its insured amount if its equipment was found to have caused the fire. The wildfire caused 86 deaths and destroyed 14,000 homes, along with more than 500 businesses and 4,300 other buildings.