This method is used to cancel attachment upload operation.
List<ResultObject> cancelUpload(List<ID> wipIds, String objectId)
wipIds: List of IDs of attachment "file" records.
objectId: Id of the parent object. You can use 15-character or 18-character ID.
Return Value: The method will return a list of ResultObject (Figure 127) which holds cancel status information for each file record.
Example code:

List<Id>wipIds = new List<Id>();
wipIds.add(ID.valueOf(uploadRequestInfos .fileWipId));
List<cg.ResultObject>resultObjects = cg.SDriveTools.cancelUpload(wipIds, objectId);