myClass.cls

global class myClass
{
    global class wrapperClass
    {
        public String name {get; set;}
        public Account account {get; set;}

        public wrapperClass()
        {
            account = new Account();
        }
    }

    @RemoteAction
    global static wrapperClass executeProcess(wrapperClass arg1)
    {
      System.debug(arg1.account.AccountNumber);
        return arg1;
    }
}

mypage.page

<apex:page controller="myClass">
<script>
var wrapper = new Object();
wrapper['name'] = 'Test';
wrapper['account'] = new Object();
wrapper['account']['Name'] = 'My Account';
wrapper['account']['AccountNumber'] = '123456789';


myClass.executeProcess(wrapper, function(result, event)
{
    if(event.type === 'exception')
    {
        console.log(event);
        return false;
    }
    else if(result)
    {
        console.log(result);
        // do something
    }
    else
    {
        console.log(event);
    }
});
</script>
</apex:page>