risolto.

codice:
private intervalSub: Subscription;


clearInterval() {
    this.intervalSub.unsubscribe();
}


    interval(2000)
        .subscribe(data => {
          this.lockService.getByTabellaLocked('mp_listini_ps', 1)
              .subscribe((res) => {
                if (res == 0) {
                this.clearInterval();
                }
              });
        });