removeEntity(entity, immediately) {
    var index = this._entities.indexOf(entity);

    if (!~index) throw new Error("Tried to remove entity not in list");

    entity.alive = false;
    this.entityRemoveAllComponents(entity, immediately);

    if (entity.numStateComponents === 0) {
      // Remove from entity list
      this.eventDispatcher.dispatchEvent(ENTITY_REMOVED, entity);
      this._queryManager.onEntityRemoved(entity);
      if (immediately === true) {
        this._releaseEntity(entity, index);
      } else {
        this.entitiesToRemove.push(entity);
      }
    }
  }
Remove the entity from this manager. It will clear also its components
@param {Entity} entity Entity to remove from the manager
@param {Bool} immediately If you want to remove the component immediately instead of deferred (Default is false)