There are a few ways to stop or cancel a scheduled job once it has been submitted.
1. In the Results tab when you hover over a scheduled job, a small X button appears. After clicking that Test Studio will prompt you for deleting the scheduled job.
2. The scheduled job is actually a file on the disk on the machine which is hosting the scheduling server. Just find and delete the file.
If you are running it locally, it will be located by default at C:\Users<yourUserName>\AppData\Roaming\Telerik\TestStudio\Scheduler\ScheduleStorage
If you are running it remotely, you have to look at the service account at
C:\Windows\System32\config\systemprofile\AppData\Roaming\Telerik\TestStudio\Scheduler\ScheduleStorage for 32-bit machines
C:\Windows\SysWOW64\config\systemprofile\AppData\Roaming\Telerik\TestStudio\Scheduler\ScheduleStorage for 64-bit machines.
3. The service itself is a REST Web Service. If you are familiar with Fiddler's Composer tab you can send a delete call to http://:8009/Jobs/. In order to get the job ID, send a GET request to http://:8009/Jobs/
Send GET request to the scheduling server
Get the ID of the scheduled job
Delete the scheduled job