Women attending the party were asked to sign a confidentiality agreement, according to a response sent from the email address listed on the Instagram post.
The photo in the Instagram post used a Bills logo behind a headshot of McCoy. The Bills issued a statement Thursday afternoon on the matter.
"We have reached out to LeSean and informed him that players are not permitted to use team marks for personal use without prior permission from the team," the statement said.
Women wishing to attend the party had to be 21 years or older and send the promoter a photograph and a link to their social media profiles in order to RSVP.
Bills players must report to training camp July 30 at St. John Fisher College in Pittsford, New York.