When a pipeline source is deleted, it deletes all the pipelines associated with the source.
To delete a pipeline source:
Go to Administration | Pipelines | Pipeline Sources and click the Actions button located at the far right.
Click Delete.
Click Confirm on the confirmation window that appears.
Note
A pipeline source cannot be deleted if any of its associated pipeline is running/waiting status. You can either cancel the run or wait for the run to complete and then delete the pipeline source.