Excel Pivot Tables

Hi - If you have a group of ages in a Pivot table eg 1 - 50 but you don't want to show them all, there is a way of grouping the ages into 1 - 10, 11 - 20, 21 - 30 etc.  I have used this feature in the past but cannot find it in 365 - has it been removed or am I missing it?  I seem to remember that you select the field, right-mouse click the field and select Group from the options given - but I cannot see it!  I would appreciate any help on this please.  Thanks