Delete Data From Particular Column

i wrote the below which deletes few data from a particular column, but then its not working when the data increases, i mean yesterday i had data upto 12000 columns and today i had more than this....still macro deleted the same as it did yesterday........is there way where its the last filled row and deletes the data present in the column P.

Sub Deleteddata()
'
' Deleteddata Macro
' Macro recorded 3/30/2007 by kaliappk
'
Selection.End(xlDown).Select
Range("O65536").Select
Selection.End(xlUp).Select
Range("P14842").Select
Range(Selection, Selection.End(xlDown)).Select
Selection.ClearContents
Range("P14841").Select
Selection.End(xlUp).Select
Columns("O:O").Select
Selection.Copy
Columns("P:P").Select
Selection.PasteSpecial Paste:=xlPasteFormats, Operation:=xlNone, _
SkipBlanks:=False, Transpose:=False
Application.CutCopyMode = False
Range("O1").Select
End Sub