QQ account cannot be deleted by user. However, it will automatically be deactivated if it is NOT logged in:
1) within 3 days after registration
2) within 45 days after only logged in on the day of registration
3) for 3 consecutive months at any time
Therefore, it is very important that you log back in your account at least once every 3 months to keep your account active if you intend to keep your QQ ID.