Delta Force - Overview
The Pentagon tightly controls information about Delta Force and publicly refuses to comment on the secretive unit and its activities.
Delta operators are granted an enormous amount of flexibility and autonomy, similar to their US Navy counterparts in DEVGRU. They will rarely wear any general uniform and civilian clothing is the norm on or off duty. This is done to conceal the identities of these "secret soldiers". When military uniforms are worn, they lack markings, surnames, or branch names. Hair styles and facial hair are allowed to grow to civilian standards in order for the force to be able to blend in and not be immediately recognized as military personnel.
This special status, which sets the force apart from the "regular army," is mentioned in the book Black Hawk Down by Mark Bowden (though less so in the film of the same name). Delta operators are allowed a significant degree of latitude in their personal grooming standards. They are allowed to grow their hair longer than what "normal" army regulations would allow.