Microsoft Excel Question

Hi i need help the issue is i need to sort a lot of data

I have two spread sheets one with new data and the other with old , a lot of rows in the old excel data need to be deleted according to the new data in the new spread sheet.

So if the data exist in the new data then i want to keep it in the old however if it does not exist in the new data then that data is no longer valid and i need to delete it from the old data base.

i am currently doing this by copy and pasting the row with the names from the new data base and matching it with the old data base one by one and it their is no match i delete the data from the old data.