Remove all Russian symbols from a PDF under Windows

Question

I have a very weird task. There is a compiled PDF document with guidelines on a mathematical subject. It is in Russian, hence it contains a lot of Russian symbols in plain text and a lot of mathematical symbols in formulas. Here is a short sample:

I need to print this document with invisible plain text, i.e. to print only the formulas and mathematical symbols. Like the following:

Document is compiled with LaTeX, but sources are unavailable. The only thing I can think of is somehow to remove or substitute all the Russian fonts in the document. But they are not embedded and I can't even locate them in my Windows! Here is the screenshot of fonts used in the document from Adobe Acrobat:

My ultimate task is to obtain a printed copy of this document. So if one could tell how to make all Russian symbols white - it would be acceptable solution. Any suggestions are welcome.

And a couple of small questions just for me to understand how it works:

1. Where are these fonts stored in my Windows 7 x64 OS? There are no such entries in my C:\Windows\Fonts\ folder.
2. What utility should I use for low-level edit of a PDF document? I.e. like fonts manipulation?

Update

Using Adobe Acrobat I've checked the fonts of shown fragment. It is SFRM1200 for plain text, SFTI1200 for italic, CMMI12 and others for mathematical symbols. So now the question is how to unembed SFTI1200 and CMMI12 fonts from the document? I expect that once I unembed them, a reader wouldn't be able to render them correctly and will substitute them on some meaningless symbols, like squares. It is even more acceptable for my task.

Answer 1

Here is my solution.

1. Use pdffonts utility from Xpdf package to list full names of the fonts in the document. Now we know that the font SFRM1200 has the full name ABEHUC+SFRM1200. I have no idea what these "full names" mean.

1. Use ghostscript utility to unembed selected fonts with the following command:

   "n:\Program Files\gs\gs9.06\bin\gswin64c.exe" ^
   -dBATCH ^
   -dNOPAUSE ^
   -sOutputFile=output.pdf ^
   -sDEVICE=pdfwrite ^
   -dPDFSETTINGS=/default ^
   -dEmbedAllFonts=true ^
   -c ".setpdfwrite <</NeverEmbed [/ABEHUC+SFRM1200 /ICZOQF+SFTI1200]>> setdistillerparams" ^
   -f POSOBSBR.pdf
   

   Thanks to this post on SO for the hint. Note how the full names of the fonts are listed under the /NeverEmbed switch.

That's how the result looks after processing:

Thanks for you help!