Loop through vector to remove element

I have a class vector that I will like to loop through to remove duplicates of a certain variable that belongs to the class.

#include <vector>
#include <iostream>
#include <functional>
#include <thread>
#include <string>

using namespace std;

struct Class {
    int x;
    string y;
};

void someFunction(vector<Class *> &arr){
    arr.push_back(new Class); // y = a
    arr.push_back(new Class); // y = b
    arr.push_back(new Class); // y = a
    arr.push_back(new Class); // y = c
    cout << "size of vector is " << arr.size()<<endl;
}

void loopDelete(vector<Class *> &arr){
    // how do i delete duplicates of arr.y in this function??
}

int main(){
    vector<Class *> foo;
    auto t1 = thread(someFunction, ref(foo));
    t1.join();
    foo.push_back(0);
    auto t2 = thread(loopDelete, ref(foo));
    t2.join();
    cout << "size of vector at end of main is " << foo.size()<<endl;
    return 0;
}

Any help or suggestion is greatly appreciated.