Q:

Remove part of a string between an start and end

Code first: 
   string myString = "<at>onePossibleName</at> some question here regarding <at>disPossibleName</at>"
    // some code to handle myString and save it in myEditedString
    Console.WriteLine(myEditedString);
    //output now is: some question here regarding <at>disPossibleName</at>

I want to remove <at>onePossibleName</at> from myString. The string onePossibleName and disPossbileName could be any other string. 
So far I am working with
string myEditedString = string.Join(" ", myString.Split(' ').Skip(1));

The problem here would be that if onePossibleName becomes one Possible Name.
Same goes for the try with myString.Remove(startIndex, count) - this is not the solution.

A:

There will be different method depending on what you want, you can go with a IndexOf and a SubString, regex would be a solution too.
// SubString and IndexOf method
// Usefull if you don't care of the word in the at tag, and you want to remove the first at tag
if (myString.Contains("</at>"))
{
    var myEditedString = myString.Substring(myString.IndexOf("</at>") + 5);
}

// Regex method
var stringToRemove = "onePossibleName";
var rgx = new Regex($"<at>{stringToRemove}</at>");
var myEditedString = rgx.Replace(myString, string.Empty, 1); // The 1 precise that only the first occurrence will be replaced

