Excel has a built-in tool for that.
In the sample data I'll use, I typed in 16 original/unique entries (actually pizza types) and copied them across 4984 rows. So I have 16 unique entries but 5000 total entries. So let's see how Excel will sort this out for us and delete all duplicate entries leaving the unique 16 entries.
Just select the entire table and goto Data menu, Remove Duplicates.