I have defined the data so that it is YYYY/MM format however it is showing in a table as every row. I want to group so that the value 2017/01 appears once instead of each row containing that information.
The formatting pattern changes only the display, it does not change the internal value. Grouping, such as a dimension values, is done using the internal values. So if you want a month only date for example, you will need to use a function that makes a single value for the month and then apply the date format. For example,
Date(MonthStart(OrderDate), 'YYYY/MM') as OrderMonth
