c# recursive function used to search for a file by name in a given directory and all subdirectories under the given root

Recursively SearchAccessibleFiles

IEnumerable<string> SearchAccessibleFiles(string root, string searchTerm) {
    var files = new List<string>();

    foreach (var file in Directory.EnumerateFiles(root).Where(m => m.Contains(searchTerm))) {
        files.Add(file);
    }
    foreach (var subDir in Directory.EnumerateDirectories(root)) {
        try {
            files.AddRange(SearchAccessibleFiles(subDir, searchTerm));
        }
        catch (UnauthorizedAccessException ex) {
            // ...
        }
    }

    return files;
} 

// use example:
// var files = SearchAccesibleFiles(@"c:\", "bugs");
// will return every file on the c drive, in an accessible directory, with a name that contains 'bugs'

Nice!
You have some mentions - https://github.com/HannibalZA/FilePurge/blob/master/FilePurge/Program.cs#L158