import {
  "golang.org/x/net/context"
  "cloud.google.com/go/bigquery"
}

func main() {
  ctx := context.Background()
  projectID := "...."
  client, err := bigquery.NewClient(ctx, projectID)
  if err != nil {
    log.Fatalf("Failed to create client: %v", err)
  }  
}

delete table:

func deleteTable(ctx context.Context, client *bigquery.Client, datasetID string, tableID string) {
	table := client.Dataset(datasetID).Table(tableID)
	err := table.Delete(ctx)
	if err != nil {
		log.Fatalf("Could not delete table %s.%s: %s", table.DatasetID, table.TableID, err.Error())
	}
}

delete tables in dataset:

func clearDataset(ctx context.Context, client *bigquery.Client, datasetID string) {
	it := client.Dataset(datasetID).Tables(ctx)
	for {
		table, err := it.Next()
		if err == iterator.Done {
			break
		}
		// NOTE: this also covers the case of a non-existing dataset
		if err != nil {
			log.Fatalf("Could not iterate dataset %s: %s", datasetID, err.Error())
		}
		err = table.Delete(ctx)
		if err != nil {
			log.Fatalf("Could not delete table %s.%s: %s",
				table.DatasetID, table.TableID, err.Error())
		}
	}
}