You can easily cancel your mySongBook subscription any time you want from your mySongBook account preferences.
- Access your mySongBook account from either Guitar Pro, mySongBook player or the mySongBook website
- Select "sign in" from the top right corner
- Fill in both your email address and your password
- Select your User name from the top right corner and choose "my account"
- Click on "Do not renew my subscription"
Note that you re-subscribe to the service later from the very same section or from any tab preview available from the website.