Login to your PaySync account and navigate to Settings:

Under 'Your Payroll Type' click the Revoke your Xero Access button to immediately revoke PaySync's access to your Xero Organisation:

You will now need to re-authorize your PaySync account with Xero if required.

This solution is referencing the Aussie Time Sheets - PaySync Software, for more information please visit: https://aussietimesheets.com.au/pages/aussie-time-sheets-paysync-cloud-payroll-integration