A renunciation of the right to letters of administration may not be revoked except upon a showing of good cause. A renunciation shall be in writing and filed with the register, and shall contain an acknowledgement that the person renouncing the right to letters understands that the renunciation may not be revoked except upon showing of good cause.
Md. R. Estate Settlem. 6-314
Code, Estates and Trusts Article, §§ 5-105 and 5-205(b).