Thanks, I solved my problem by replacing "pathToFile" with BinarySave's "Application.persistentDataPath + "/" + filename.Value" in the script body, also I added public string Filename, thus it is solved, now I can delete my Binary Saves successfully.
However outside this issue, still I don't know how to write a correct "FilePath" to Delete a File (is it "C:\Users\[user]\AppData\...?") other than replacing the Filepath with Application.persistentDataPath or anything specific, I hope somebody can explain.
Briefly, the question is, what should we write for Filepath, should it be "C:\Users\[user]\" or something else, because we can't write explicit filepath as we have in our OS, but it must be universal.