Instagram makes it quite difficult to delete your account, providing instructions to use a button that has been removed. (This isn’t new shenanigans on their part though.)
Here is a post about it on Reddit.
Here is the direct link to where you can request account deletion (it gave me a message that the account will still exist for one more month in case I change my mind, then be auto-deleted.)
https://www.instagram.com/accounts/remove/request/permanent