If you always want to remove the first two, LINQ probably provides the simplest approach:
string allButFirstTwoWords = words.Skip(2).ToArray(); // Or ToList, or nothing...
Note that you can't "remove" values from the array itself, as an array always has a fixed size after creation. The code above creates a new array with all but the first two words.
Of course, you can do it all in one go:
string[] words = Receipt.Split(' ', ',', '-').Skip(2).ToArray();
Personally I'd usually use a List<string> instead, as it's more flexible:
List<string> words = Receipt.Split(' ', ',', '-').Skip(2).ToList();
If you're just going to iterate over it, you don't need to convert it to an array or a list at all:
IEnumerable<string> words = Receipt.Split(' ', ',', '-').Skip(2);