Metaflac.exe

a question, to editing flac with metaflac.exe How do I select the .flac file without changing the file name to flac1.flac?

I do this: metaflac.exe --remove-all --dont-use-padding flac1.flac

I mean, How do I do it with the filename with spaces? ej: Syd Barrett - The Madcap Laughs.flac

You are working on the DOS commandline, ...
therefore you should do it as the DOS commandline processor needs it:
enclose a parameter, which is a string, ...
which contain one or more space characters, ...
into double apostrophes.

You can learn from the DOS batch script there ...
How to decrease the tagsize after deleting coverart

DD.20170323.0808.CET