If you live in New York, any harm in dropping it off quickly and politely, leaving it with the receptionist?
Ask. Agents feel differently about this, usually depending on how often they actually come into the office (as opposed to working from home) and whether they actually have a receptionist. I used to work for an agency that did not have one, and anyone could walk in, and we all want to avoid the awkward conversation with the author we are probably going to reject, statistically. My current boss works in a building with a lot of different small offices and does have a receptionist for the building, so she allows drop-offs, but only when she knows to expect them and ask if there's anything behind the desk for her.