Deletes a variable from a documents variable dictionary.
Ensure that the variable is no longer used by the queries in the document.
DELETE <webiURL>/documents/{documentId}/variables/{variableId}
Where:
Response type: application/xml or application/json
The response is a message stating the success or failure of the request.
DELETE <webiURL>/documents/8022/variables/L9
<success> <message>The resource of type 'Variable' with identifier 'L9' has been successfully deleted.</message> <id>L9</id> </success>