let by

let (one) by

To allow one to pass by or around (someone or something). I need to get into the building to retrieve my briefcase—please let me by! I didn't want to drive any faster on the highway, so I moved closer to the curb to let the cars behind me by.
See also: by, let

let someone (get) by

 and let someone pass by
to permit someone to pass. Please let me get by. I am in a hurry. Let the paramedics by, please.
See also: by, let