Google Play Store:
Please log in your Google Play account and find "CamScanner premium account" in "subscriptions". Then you can cancel the subscription there.

Please note: The cancellation will come into effect in the next month (or year), because the subscription for the current month (or year) has already been in force and cannot be cancelled.

We developers are not able to help check user's subscription or cancel it; it is all under Google's control. If you failed to cancel it, please contact Google Play support team for further assistance: https://support.google.com/googleplay/answer/1267137

Alipay/WeChat:

This service is supported by Alipay/WeChat, so you need to cancel it from Alipay/WeChat as follows:

Alipay: Open Alipay app on your phone-->tap "Me"-->"Settings"-->Payment Settings-->Auto Debit-->Find "合合信息免密支付" or“临冠免密支付”-->解约。

WeChat: Open WeChat app on your phone-->tap "Me"-->"Pay"-->tap the "..." icon on top right --> Manage Playments -->Auto Debit-->Find "扫描全能王高级账户包月自动续费"-->tap "close service"。

If you didn't see any related item in Auto Debit, it means you didn't subscribe to the service and won't be charged by month/year automatically.