code: def _del_scalars(self, run_id, prefix):
      self._db.execute(
          """
            DELETE from scalar
            WHERE run = ? AND prefix = ?
          """,
          (run_id, prefix),
      )
  
imports: import logging
  import os
  import sqlite3
  from guild import run_util
  from guild import tfevent
  from guild import util
  from guild import var
label_desc: Use image node_id 6 for calling the ScalarReader obj's underlying member method code with example usage: obj._del_scalars(run_id, prefix) without return types