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for i := 0 to Form1.ComponentCount - 1 do
begin
  if Form1.Components[i] is TLabel then
    if TLabel(Form1.Components[i]).Parent is TPanel then
      TLabel(Form1.Components[i]).Free;
end;					

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[...]
if TLabel(Form1.Components[i]).Parent = Panel1 [...]					

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  i := 0;
  while i < Form1.ComponentCount do
  begin
    if Form1.Components[i] is TLabel then
      if TLabel(Form1.Components[i]).Parent is TPanel then
        if TPanel(TLabel(Form1.Components[i]).Parent).Name = 'Panel1' then
        begin
          TLabel(Form1.Components[i]).Free;
          i := i - 1;
        end;
      i := i + 1;
  end;