If you don't need the multiline you can disable it and shouldn't have this problem.
You could also remove them like this:
string text = textRange.Text.Replace(Environment.NewLine, "");
Also if you only want to remove the last ocurrence you can use a function like this:
public static string ReplaceLastOccurrence(string Source, string Find, string Replace)
{
int Place = Source.LastIndexOf(Find);
string result = Source.Remove(Place, Find.Length).Insert(Place, Replace);
return result;
}
And use it like this.
string text = ReplaceLastOccurrence(textRange.Text,Environment.NewLine,"");
Every time you have a you will get a New Line at the end, so make sure you handle it acordingly.