The former Liverpool player was favourite to take over at the third division club, but they are looking for somebody with managerial experience.
"The club is in a precarious position and for Stan to take the reins at this time would be a risk impossible to quantify," said Martin.
"After careful consideration, the board and I feel this is not the moment for Stan Collymore to manage Southend United. That role should fall to a person with considerable experience."