I am trying to escape markups and unicode charcaters from the string using the Regular expression like below
string b = Regex.Replace(StNameTag, "<[^>]+>|\u200B|\n|\t|\r", string.Empty);
But the issue is its not escape some characters like  
and some string even has
ED5D6EB4918943C197E874EF6414E351 .ExternalClass p.MsoNormal, ED5D6EB4918943C197E874EF6414E351 .ExternalClass li.MsoNormal, ED5D6EB4918943C197E874EF6414E351 .ExternalClass div.MsoNormal {margin-top:0in;margin-right:0in;margin-bottom:8.0pt;margin-left:0in;line-height:107%;font-size:11.0pt;font-family:"Calibri",sans-serif;}ED5D6EB4918943C197E874EF6414E351 .ExternalClass .MsoChpDefault {font-family:"Calibri",sans-serif;}ED5D6EB4918943C197E874EF6414E351 .ExternalClass .MsoPapDefault {margin-bottom:8.0pt;line-height:107%;}ED5D6EB4918943C197E874EF6414E351 .ExternalClass div.WordSection1 {} ABCD
I will need only ABCD from the above string. How can I escape them.