Sorting Purchases By Customer / By Date

I have a spreadsheet that contains over 3000 customers. On this there is much data...but what I am interested in is purchase date. The problem I am having is that customers have purchased multiple times and have multiple purchase dates. I was wondering if there was a way to get rid of all but the most recent purchase dates for each customer...thus having only one line per customer as opposed to 5 lines per customer?

In other words: Jon purchased on 1/2/14; 2/4/14 & 5/8/14
Bill purchased on 2/17/14; 3/19/14 & 4/21/14
Tom purchased on 4/2/14; 5/1/14 & 6/5/14

I need to get rid of the oldest dates and keep one line item by most recent purchase date for each customer...so instead of having 300o line spreadsheet I will only have 1000 lines.