removeContainerProtection(containerID) {
    const index = this.formBuilder.preserveTempContainers.indexOf(containerID)
    if (index !== -1) {
      this.formBuilder.preserveTempContainers.splice(index, 1)
    }
  }
Remove one reference that protected this potentially empty container. There may be other open fields needing the container
 @param {string} containerID