HI!
There's no option to protect files.
If you are giving the files to others and you dont want to send the browser history, you can create a new file using several methods.
1-Create a SUBSTITUTE/SIMPLIFICATION file. You can also simplified the geometry: remove holes, fillets, components etc.
2-Create a DERIVE file. You can remove parts if you want.
These files will be linked with the source file (so it can be updated), but other persons you send the file, only see the solids/geometry, not the browser history.
3-Save as STEP file, it's not associative with the source (doesn't update, every time you change the source, you have to create a new Step).
All of the 3 options can be used in parts or assemblies.
CCarreiras