uses DBITYPES, DBIERRS, DBIPROCS;

procedure TForm1.ShowDeleted(Table: TTable; ShowDeleted: Boolean);
var
  rslt: DBIResult;
  szErrMsg: DBIMSG;
begin
  Table.DisableControls;
  try
    Check(DbiSetProp(hDBIObj(Table.Handle), curSOFTDELETEON,
      LongInt(ShowDeleted)));
  finally
    Table.EnableControls;
  end;
  Table.Refresh;
end;

procedure TForm1.CheckBox1Click(Sender: TObject);
begin
  ShowDeleted(Table1, CheckBox1.Checked);
end;

//или

procedure DeletedRecords(Table: TTable; SioNo: Boolean);
 begin
   Table.DisableControls;
   try
     Check(DbiSetProp(hDBIObj(Table.Handle), curSOFTDELETEON, Longint(SioNo)));
   finally
     Table.EnableControls;
   end;
   Table.Refresh;
 end;