No problem! If you email us within 1 hour of making your order there is a good chance we will be able to cancel part of it. Hit us up at hello@blackmilkclothing.com with your BMC order number and which item(s) (including the sizes) you want to cancel.
Note that our warehouse ninjas are sometimes even speedier than we expect so we can't guarantee that we'll be able to make changes, but the more quickly you can get in touch with us, the better chance we have!