#pragma GCC optimize("Ofast")
#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <queue>
#include <cstdio>
#include <ctime>
#include <assert.h>
#include <chrono>
#include <random>
#include <numeric>
#include <set>
#include <deque>
#include <stack>
#include <sstream>
#include <utility>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
#include <tuple>
#include <array>
#include <bitset>
using namespace std;
typedef long long int ll;
typedef unsigned long long ull;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll myRand(ll B) {
    return (ull)rng() % B;
}
inline double time() {
    return static_cast<long double>(chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now().time_since_epoch()).count()) * 1e-9;
}

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int q; cin >> q;
    while(q--){
        int n; cin >> n;
        string s; cin >> s;
        vector<char> v;
        reverse(s.begin(), s.end());
        for(char c:s){
            if(c == 'B'){
                v.push_back(c);
            }
            else{
                if(v.size() and v.back() == 'B'){
                    if(v.size() >= 2 and v[v.size()-2] == 'B'){
                        v.pop_back();
                    }
                    else{
                        v.push_back(c);
                    }
                }
                else{
                    v.push_back(c);
                }
            }
        }
        for(int i=v.size()-1;i>=0;i--){
            cout << v[i];
        }
        cout << "\n";
    }
}