The Western Mail claims that the county's second XI coach Adrian Shaw will be promoted to take charge of the first-team.
Derrick, who joined the county in 2002, is expected to take up a new position with the Cricket Board of Wales after he is relieved of first-team duties.
Arguably the most successful coach in the club's history, Derrick led Glamorgan to the one-day league in 2002 and 2004, but results have tailed off in recent seasons and the county have lost 21 of their last 32 Championship matches, winning just three.
Last season they finished one place off the bottom of division two in the Championship and were relegated in the Pro40 league.
The county is also in serious financial difficulty, with the costs of reaching the standards required to host an Ashes Test in 2009 meaning that they cannot afford overseas players for 2007, and as a result any appointment is likely to be in-house.
When quizzed on a possible change two months ago Glamorgan chairman Paul Russell said: "Adrian is a very capable coach. It would not be beyond the bounds of anyone's imagination that one solution would be to give him more responsibility."
Glamorgan chief executive Mike Fatkin refused to confirm or deny the speculation surrounding Derrick's position, and said no announcement will be made until captain David Hemp returns from international duty with Bermuda.