function FilterMemo(S: string): string;
var
  TagBegin, TagEnd, TagLength: integer;
begin
  TagBegin := Pos( '<', S);
  while (TagBegin > 0) do begin
    TagEnd := Pos('>', S);
    TagLength := TagEnd - TagBegin + 1;
    Delete(S, TagBegin, TagLength);
    TagBegin:= Pos( '<', S);
  end;
    Result := S;
end;
 
Memo1.Text := FilterMemo(Memo1.Text);