C# Method to delete duplicate characters in strings

#region Delete duplicate characters
string s = "sdfffffsrlkjesgljfdg03940864e5=_0R9DTGR98YUI\\|||'\\???fdf///"; 
("<br/>String：" + s + "<br/>Result："); 
IEnumerable<char> distinctList = (); 
foreach (char a in distinctList) 
{ 
    (()); 
} 
 
//Use the removal method
for (int i = 0; i < ; i++) 
{ 
    while (((i, 1)) != ((i, 1))) 
    { 
        s = (((i, 1)), 1); 
    } 
} 
("<hr/>Result：" + s); 
#endregion