You can view a list of all users whom you or other owners have blocked from your organization.
In the top right corner of GitHub, click your profile photo, then click Your profile.
On the left side of your profile page, under "Organizations", click the icon for your organization.
Under your organization name, click Settings.
In your organization's Settings sidebar, click Blocked users.
Under "Blocked users", review the list of users who are blocked from your organization.