If you’re looking to delete your Snapchat account permanently, follow these steps. Your Snapchat account will first be deactivated. After 30 days of deactivation, your Snapchat account will be deleted permanently.
Note: at this time, you cannot delete your Snapchat account from the app.
From the Snapchat Website:
If you’re sure you want to delete your account, please enter your username and password below, and then press Continue. Your account will be deactivated, which means friends won’t be able to contact you on Snapchat. After 30 days, your account will be deleted. If you’d like to reactivate your account before that happens, just log into Snapchat.
So, if you device before 30 days you want to keep your Snapchat account, just log back into it on the Snapchat website!