Simple SqlHelper which wraps ADO.NET methods
Nesting.
You can reduce nesting by stacking the using blocks, like this:
    using (var connection = new SqlConnection(connectionString))
    using (var command = new SqlCommand(cmdText, connection))
    {
        try
        {
            command.CommandType = cmdType;
            command.Parameters.AddRange(commandParameters);
            connection.Open();
            return await command.ExecuteNonQueryAsync();
        }
        finally
        {
            connection.Close();
        }
    }


I like your usage of var, and the fact that you've wrapped the IDisposable stuff in using blocks. However this is overkill:

    finally
    {
        connection.Close();
    }


Because the connection is wrapped in a using block, the connection will be cleanly closed and disposed, whatever the reason is for the code to reach the end of the using scope. In other words, you can also ditch the try block, and further reduce nesting:
    using (var connection = new SqlConnection(connectionString))
    using (var command = new SqlCommand(cmdText, connection))
    {
        command.CommandType = cmdType;
        command.Parameters.AddRange(commandParameters);
        connection.Open();
        return await command.ExecuteNonQueryAsync();
    }

That's because a using block is a language shortcut for... a try...finally block.

The XxxxxHelper Syndrome
The problem with a static class called SqlHelper, is that over time, it becomes a dumping ground for anything remotely related to SQL; it grows hair and tentacles, and becomes a huge mess before you even notice: &quot;Helper&quot; is simply too vague of a name to result in anything cleanly focused.
I would suggest renaming it to something like SqlCommandWrapper - then it's far less likely to become bloated with things that have nothing to do with executing a SqlCommand, but might be remotely related to SqlWhatever.