It depends on how many lines/names on you database, and how many duplicates are expected.
If not very big the use conditional formatting on the phone number so the duplicates are highlighrted, the delete the rows. For a big database you need VBA solution. Someone else here can help you with VBA if needed.
you can change the row by changing the letter in the brackets
Dim i As Long
Dim row As Long
row = Cells(Rows.Count, "A").End(xlUp).row
For i = row - 1 To 1 Step -1
If Cells(i, "A").Value = Cells(i + 1, "A") Then
My database reads like this. Col A = Phone Number Col B = Cust Name Col C = Cust Address Col D =City Col E = State Col F = Zip And the whole deal is sorted by phone number. So it's really easy to tell which ones are the duplicates but there's just SO many, I simply don't have time to go through and delete all the duplicates individually. There's over 7500 customers in this database.
I beleive you may be able to simply select the phone numbers column (COL A) then click the Data>Filters>Advanced Filters menu, now select the unique values only tick box, this will strip out all the duplicates in column A.