How to convert multiple UTF-8 files to ANSI format?

Question

I really don't know much about computer, but in order to use another converter I need my files to not contain any UTF-8 character, I thought this PowerShell command did the job:

foreach($i in ls -name ./*.osu) { get-content ./$i | out-file -encoding ascii -filepath ./$i }

but it didn't convert the UTF-8 characters into ANSI characters, it doesn't matter it's a question mark as long as it is converted.