Her announcement comes at the end of a week which has already seen two regional newspaper editors standing down. The Newcastle Evening Chronicle's Paul Robertson and the Hull Daily Mail's John Meehan also left their posts this week.
Smith has been replaced by Keith Harrison, deputy editor of the Star's sister title the Express and Star. A statement issued by the company today said that she had stepped down to "pursue other interests".
John Simcock will stay on as deputy editor under Harrison.
"It has been a privilege to work for the MNA in so many roles during my 32 years with the company," Smith said.
"I will certainly miss my team, of whom I have always been immensely proud, but I am delighted to wish the company every deserved success in the future."
Smith joined the MNA in 1979 as a trainee with Shropshire Weekly Newspapers, before moving to the Wolverhampton Express & Star and later being made editor of the Shropshire Star.
MNA announced in April that it was seeking 95 voluntary redundancies across the titles in the region, 30 of those at the Shropshire Star. The total number of redundancies sought amounts to 10 per cent of the entire workforce.
But by June only 41 members of staff had come forward, with the company turning to compulsory redundancies to make up the difference.
Members of the National Union of Journalists at the newspapers voted unanimously to ballot for strike action over the proposed cuts.