Deleting cell contents starting with numbers VBA

Try:

Sub b1358354c()
Dim i As Long
Dim n As String
Dim va

va = Range("A1", Cells(Rows.Count, "A").End(xlUp))
For i = 1 To UBound(va, 1)
    n = Trim(Val(va(i, 1)))
    If Len(n) > 4 Then va(i, 1) = n
Next
Range("B1").Resize(UBound(va, 1), 1) = va

End Sub