import sys
input = sys.stdin.readline

T=int(input())
for tests in range(T):
    N=int(input())
    S=input().strip()

    T=[]

    for s in S[::-1]:
        if s=="A" and len(T)>=2 and T[-1]=="B" and T[-2]=="B":
            T.pop()
            continue
        else:
            T.append(s)
    print("".join(T[::-1]))