The Athlone man brought Sligo as far as the FAI Cup semi-finals this year.
Sligo Rovers and Tommy Hewitt have parted ways after just one season together in the Women's Premier Division.
The former Athlone Town manager brought the Bit O' Red to this year's FAI Cup semi-finals before narrowly going out at the hands of his former club last month.
Silgo have failed to pick up a win over the course of this year's league campaign, but did pick up creditable draws against Shamrock Rovers and Peamount United in their last two games.
Hewitt has been on the record recent saying the club needed investment to progress.
He departs with Sligo cast adrift by 11 points at the bottom of the table.
They face Cork City and Wexford in their final two games.