The 33-year-old centre-back left County this week to pursue a career outside of the game after realising he would be back-up to Scott Boyd and Brian McLean.
Munro had made six starts this season but Adams is content with his options at the back.
Adams said: "We have got good cover in that area. We have Steven Saunders, Brian McLean, (Branislav) Micic and Boyd, and (Mihael) Kovacevic and Ben Gordon as well. So we have good cover in the back four at this time.
"It was a difficult decision for Grant. You want to play football all the time. He has been given the opportunity to try to progress with a job elsewhere outside football.
"He has got another 30 years to work and he wants to get that done sooner rather than later."