Regex for removing only specific special characters from string

Question

I\'d like to write a regex that would remove the special characters on following basis:

• To remove white space character
• @, &

Answer 1

use a character set [charsgohere]

string removableChars = Regex.Escape(@"@&'()<>#");
string pattern = "[" + removableChars + "]";

string username = Regex.Replace(username, pattern, "");