Dempo, who led 4-0 at half time, scored through Tolgay (16th, 30th), Roberto Silva(18th) and Clifford Miranda (25th).
Sporting clube de Goa, who lost to Mohammedan Sporting in their last outing, could not afford to lose further as that would see them slip in the points table. Sporting started promisingly, but Kalu Ogba and Boima Karpeh missed the target narrowly.
Tackles from their defenders Deepak Devrani and Keenan Almeida saw Sporting concede two penalty in a span of two minutes, and Dempo scored off both.
Tolgay then picked a long ball from Miranda beat the rival defender and goalkeeper Ravi Kumar, to complete the rout.