In your example the last cell in column 2 is also the last cell in the table. Looking at your previous question, I'm going to assume that is always the case. I'm also going to assume there are no trailing spaces on that last cell so this simple code would work.
Code:
Sub CleanseTheColon()
Dim aTbl As Table, aRng As Range
For Each aTbl In ActiveDocument.Tables
Set aRng = aTbl.Range
aRng.End = aRng.End - 2
If aRng.Characters.Last = ";" Then aRng.Characters.Last = "."
Next aTbl
End Sub