Disconnecting Google Sheets and Zoho Survey will stop all your existing surveys from pushing data to Google Sheets. The permissions you've provided to Zoho Survey to make changes to your Google Sheets (by pushing responses to it) will be revoked.
To disconnect Google Sheets and Zoho Survey:
Go to Setup under your Profile in the top right corner of your screen.
Click Apps and Services.
Click Disconnect in the Google Sheets section.
Click Yes, Disconnect Integration.