How can i delete duplicate value in vector except last one

I have a groups of coordinates(x,y,z) value in a vector in which first value and last value should be same but there is another coordinate in vector that is also common to first and last element in vector. i want to delete duplicate element in vector without changing the order.

below is my vector.

std::vector<std::vector<mi::math::Vector_struct<mi::Float32, 3> >> points;