Here’s the link to delete your Instagram account permanently, and if you want to temporarily deactivate your account then just click on the option for ‘temporarily deactivate your account’ which is given in this link.
LINK – https://www.instagram.com/accounts/remove/request/permanent/
If you wan’t detailed tutorial for deletion of Instagram account permanently then you must see the youtube video tutorial from this link. ( CLICK HERE FOR WATCHING TUTORIAL VIDEO )