The 33-year-old centre-back, who joined the Pilgrims from Harrogate Town in the summer, has departed after cancelling his contract at The Jakemans Stadium.
He moves on with the club's best wishes for the future.
McCombe's exit was preceded by the arrival of Harrogate centre-half Toby Lees (21) on a month's loan on Tuesday. He made his debut late on in the 2-0 defeat to Leamington.
Lees will remain with the Pilgrims until September 8 initially.
Goalkeeper Dylan Parkin, meanwhile, has joined Evo-Stik Division One East side Cleethorpes Town on a two-month loan deal.
Parkin is scheduled to be with Clee until October 6 but the Pilgrims do have a 24-hour recall clause in the deal.
Updated 08:15 - 10 Aug 2018 by Craig Singleton