You can use a macro.
But in your case, you don't need to scan through all 4000 entries which could be time consuming. You can use another approach, which is to find and replace all numeric value in the cells. ie. from 0 to 9.

So, select the range of cells to clean up, and run the following macro.

Sub Macro1()
Dim tmp As Integer
With Selection
For tmp = 0 To 9
.Replace What:=tmp, Replacement:=""
Next
End With
End Sub