First try to stop the SonarStart.bat by using Ctrl+c as suggested , and then try to open localhost:9000 ( or whichever port you configured sonar server).
If it is still opening then go to task manager and search for wrapper.exe service and stop the service, if no service or app is found then goto:
Task manager>Details> and stop all java.exe process.
Note: If you running many java applications, right-click the java.exe and choose goto service, and stop only those java.exe that belongs to AppX deployment.