Unless you are using a private account, any photos published on Instagram are visible to all users on the social network. However, similar to other social platforms, Instagram also provide a feature to block unwanted users from viewing your photos or contacting you.
Block Someone on Instagram
When a user is blocked on Instagram, he or she will not be able to view any uploads you make to your account. He or she will also be unable to search for your profile on the social network.
If you'd like to proceed with blocking a particular user, you can do so by simply opening their profile page, tapping on the Menu button (3 dots), and then selecting Block:
Confirm by tapping on Yes, I'm sure. Your settings will be effective immediately.