I assume you have Moroccan citizenship by filiation. The relevant law seems to be Dahir n° 1-58-250 du 21 safar 1378 (6 septembre 1958) portant la Code de la nationalité marocaine. It is not clear what the actual procedure is. Chapter 4 covers renunciation and involuntary loss (for e.g. insulting the King). Art. 19 includes some possible cases: case 1, an adult Moroccan who has voluntarily acquired a foreign nationality abroad and is authorized by decree to renounce Moroccan nationality. Article 25 indicates that petition the Minister of Justice, who will determine whether the legal conditions are met, and "to assess whether the favor sought is justified from the national point of view".
However, if you were born in the US (or any other jus solis jurisdiction) to Moroccan parents, you did not acquire that citizenship voluntarily, in which case if the Minister of Justice is a stickler for detail, you do not satisfy the requirements for renunciation of citizenship.