Why Do You Titrate Calcium Oxalate With KMnO4 Permanganate? Purpose?

Oxalic acid is a reducing agent, it reduces permanganate to manganous ion. Thereby changing the colour of KMnO4 solution, acting as a self indicator

2 MnO4-(aq ) + 5 H2C2O4(aq ) + 6 H3O+(aq ) --> 2Mn2+(aq ) + 10 CO2(aq ) + 14 H2O

The equation for the oxidation of oxalate by permanganate in acidic solution.