If you no longer need a stream, then delete it. Also, by deleting a stream, it won't take up quota and you won't be billed for it in the future.
Delete a stream
Go to the Streams page in the Google Cloud Console.
Go to the Streams page
Click the stream that you want to delete.
As a best practice, in the Stream status pane of the Stream details page, verify that the status of the stream isn't
Running. If it is, then pause the stream.
In the dialog box, enter
Delete in the text field, and then click DELETE.