Go to your User Settings and choose Account Removal > Disable Account.
Your account is put on pause when it is disabled. After login in, you can reactivate it by doing as instructed. Remember that accounts that are dormant for two years are removed, so you'll need to reactivate your account if you wish to preserve it (but you can disable it again after this if you like).
You will stop getting Discord's notifications after you disable an account. You can still send and receive friend requests, though, and any that you receive while your account is disabled will be ready for you when you re-enable it.
When you delete your account you will be permanently erased(after a bit of time). It can't be undone.
