Go to the Snapchat Accounts Portal: https://accounts.snapchat.com
Sign in with your Snapchat username and password
Select Delete My Account
Enter your username and password again if prompted
Click Continue
Your account will be deactivated for 30 days
Do not log in during the 30-day deactivation period
To reactivate, log in again within 30 days
After 30 days, the account will be permanently deleted