Ogba struck in the fifth and 68th minute while Joseph Pereira found the target in the second-half stoppage time to complete Sporting Clube de Goa's scoreline.
Ranty Martins found the lone reply for United in the 15th minute.
There was more setback for the home outfit as substitute midfielder M Zakeer was sent off in the 87th minute with a red card.
In the absence of Costa Rican World Cupper Carlos Hernandes and suspended Nigerian Bello Rasaq, United were dealt a severe blow, with Ranty being the lone foreigner in the side.
Sporting Clube, on the other hand, were in a resurgent mode as the win gave the Goan side an opportunity to seek a way out of the relegation zone.
Kalu scored from the spot after United's India team goalkeeper Subrata Paul fouled on a surging Joseph Periera inside his own box.
Ranty got the home team back in contention when he scored from a Lalkamal Bhowmick rebound as both the teams were locked 1-1 at the break.
United had the first chance in to get into the lead, in the 52nd minute, but midfielder K Asif shot wide from close to deny them.
Kalu made no mistake in the 68th minute when he dribbled past two United defenders and capped a brilliant solo effort to snatch the lead as the home side was reduced to 10 players in the 87th minute.
Pareira scored one more time, in the injury-time, to complete the rout.
