The 38-year-old brings to an end her four-year association with the club, after joining from Tottenham Hotspur in 2022.
In total, Williams made 90 appearances for the Reds, scoring 21 goals.
She helped us claim Women's FA Cup glory in 2024, as we beat her former club Spurs 4-0, with Rach scoring our third goal at Wembley Stadium.
Rach has become part of the furniture at Carrington, helping to bring together members of the squad over recent seasons.
The ex-Birmingham striker scored pivotal goals for the Reds, including her 88th-minute winner against Brighton in the FA Cup semi-final in April 2023.