The Star reported last week that Mmemezi was to be dismissed for the abuse of state funds and for damaging a government vehicle, following the return of the premier, Nomvula Mokonyane, from a state trip to China.
It had also been claimed that Mmemezi used government funds to buy a painting – worth R10 000 – from a McDonald's in Pretoria.
In a statement on Wednesday, he apologised for personal purchases made on a government credit card.
"After consultation with my organisation, through the ANC integrity committee and the provincial office bearers, I have decided that the most honourable thing to do under these circumstances is to step down from the executive council as the MEC [provincial minister]," he said.
Mmemezi was also linked to an accident involving West Rand teenager Thomas Ferreira, who was hit by an official Gauteng government vehicle in November 2011.
Wide financial issues than unauthorised or inappropriate personal spending are plaguing the province, however. It was reported on Wednesday that Gauteng municipalities were owed more than R26-billion with households owing 70% of the debt, businesses 23% and government 2%.
Democratic Alliance local government spokesperson Fred Nel told the Star: "Debt owed to municipalities in Gauteng rose by R4.26-billion (19.2%) in the last financial year, between March 31 2011 and March 31 2012."
With the debt being older than 90 days, it posed a serious problem since debt that old was not usually recoverable.
The information was sourced from Gauteng provincial gazettes, he said.
The city of Johannesburg was owed more than R11.2-billion by the end of the last financial quarter, compared to R8.4-billion last year.
The Ekurhuleni metro was owed R8.1-billion, up from R7.2-billion; the City of Tshwane R3.6-billion from R3.2-billion, Emfuleni R2.3-billion from R1.9-billion, and Mogale City R612-million.
The West Rand district municipality was owed R8.2-million, Randfontein municipality R220-million, Lesedi municipality R163-million, Westonaria R110-million and Midvaal R78-million.
Merafong was owed R490-million last year. There were no figures for this year, according to the newspaper.
The Sedibeng district municipality was owed the least, R652 000, down from R1.7-million last year.
Nel said the Democratic Alliance wanted the South Africa Revenue Service to look at linking municipal arrears with income tax returns since this would be cheaper than debt collection, the Star reported.
Gauteng local housing minister Humphrey Mememzi told the provincial legislature in May his department and the provincial treasury were implementing a debt strategy to ensure departments paid their municipal rates and services. – Sapa