To do this, use Text to Columns. Select the column where you have the dates, go to Data, Text to Columns, select Delimited in Step 1, in Step 2 make sure that the “other” checkbox is activated and put a “/” in the box to the right of the other checkbox. Finally, in step 3 select a Destination cell (It defaults to the current cell). Hit Finish and that’s it.
If you format column C as a date (you can use a custom format of yyyy/mm/dd if you want) then you can use the formulas =YEAR(Cn), =MONTH(Cn) and =DAY(Cn) to give you the separate values.