Given your first paragraphs about forced learning, your last one about how you don't know how to fix your problem in Windows so you just leave it broken is a strange contrast.
If the subtitles are plain text with annotations on their own lines, a one line command will strip them out:
for /f "delims=" %x in subtitles.txt do @echo %x | @find /V "[" >> subtitles2.txt
That's just a cached thought: "Windows CLI sucks, don't even bother". In hindsight that sounds a bit silly. And I know Bash better (along with sed, grep, find…). Anyway, thank you, I'll try this command.
Nevertheless, I think there is a reason for my erroneous cached thought: the overwhelming emphasis on the GUI.
If the subtitles are plain text with annotations on their own lines, a one line command will strip them out:
And if you do need sed and regexes, get sed for windows: http://unxutils.sourceforge.net/