If you would like to delete Sharepoint Timer Job Definitions follow these steps:
1. Go to Central Administration > Operations
2. Click on Timer Job Definitions
3. In this page go to the job that you wish to delete
4. Copy the GUID shown in the URL field of the browser (something like below:
http://centraladmin.company.com/_admin/JobEdit.aspx?JobId=99346da8%2D1cba%2D4691%2D8c18%2D4e257650aa72
5. Copy to NotePad and replace the %2D characters by a dash "-"
5. Then go stsadm and run the following command:
stsadm.exe -o deleteconfigurationobject -id <ObjectGUID>
The command stsadm.exe -o deletessptimerjob is for deleting Shared Services timer jobs. Which rarely is needed...
Good luck!