Reid, who had managed Ayr in the Scottish Leagues for almost five years between 2007 and 2012, replaced Kevin Wilkin, who had moved to Wrexham, in April, but has been given only seven games this season before they called time following a 4-0 defeat at Torquay.
His departure was revealed in bizarre circumstances. Reid was due to attend a supporters forum last night alongside chief executive Ian Neale, but it was Neale who addressed the meeting.
"You'll notice someone is missing from the stage this evening," he announced. "It's been a tough start to the season and to see a disappointing start has been difficult for the supporters as well as the board.
"We are not ones to rush into decisions, however, we've been in a three hour meeting with Brian this afternoon and agreed by mutual consent that he will leave the club this evening. "
He did add, to the 25 supporters present: "Brian is a genuine gentleman and as disappointed as we are. I personally take responsibility for his appointment. I was the person who interviewed Brian and gave him the job so his failure in the role is unsatisfactory for the club now, and I take that responsibility."