Before the issue of letters of conservatorship to a testamentary conservator relieved from giving bond and sureties or at any time thereafter, if the judge of probate deems it necessary for the safety of such minor child or children, he or she may require of such conservator bond with sufficient sureties, or, on the application of such minor child or children by next friend and for good cause shown, he or she may require of such conservator bond with sufficient sureties. In either case, if such conservator fails for 10 days after the requisition of such bond to give the same, the judge of probate must withhold from his or her letters of conservatorship or, if letters have issued, must remove him or her and recall and revoke such letters.