I always advocate for deactivation but if you’re sure you no longer need your Instagram account and everything in it, you could as well permanently delete your profile.
This will erase your photos, comments, bio……..literally everything and you will never be able to recover anything. The username will also permanently disappear and no one will be able to use it in future; including you.
How To Delete Instagram Account:
The mobile applications have no way of deleting your account. But the web interface for both PC and mobile allows you to access the account Deletion page.
You might be required to sign in if you haven’t already. Then follow the instructions in the video (or on the page) to permanently delete your Instagram account.