Instagram states in its Privacy and Safety Centre that you can revoke the license you have given them by deleting your account or your content. The content will be removed from your activity and your followers will no longer see it. However, if any of your friends have shared the content, then the shared copy will still be available and can be accessed and downloaded by others. To completely remove content, then all who have shared the content will also have to delete the shared copies. Once the content is deleted, Instagram can no longer make use of the content in any way.