What you have is a person who died intestate (without a Will). You need to open a probate with the probate court in the county where your father passed away. When it comes to appointing the executor, the judge will look to the surviving spouse, and if there is none or the surviving spouse is disabled, they will look to children and other relatives. Therefore, you can petition the court in the probate to appoint you as executor.
In Maryland you need to go the Register of Wills/Orphan's Court and have an estate opened and request that you be made personal representative. Given the information you provided, there should be no difficulty in having yourself appointed. As personal representative you will be able to dispose of your father's property.
Below is a copy of the first part of the statute that governs who can be Person Representative (Executor). Testate means with a will; intestate means without a will.
In granting letters in administrative or judicial probate, or in appointing a successor personal representative, or a special administrator as provided in Subtitle 4 of Title 6, the court and register shall observe the following order of priority, with any person in any one of the following paragraphs considered as a class:
(1) The personal representatives named in a will admitted to probate;
(2) The personal representatives nominated in accordance with a power conferred in a will admitted to probate;
(3) The surviving spouse and children of an intestate decedent, or the surviving spouse of a testate decedent;
(4) The residuary legatees;
(5) The children of a testate decedent who are entitled to share in the estate;