Above answer already Solved your Question.
I am just giving the Function which will Solve your Problem.
Public Function GetSubString(Bvyal S1 as String)As String
Return (S1.Remove(S1.LastIndexOf(" ")))
End Sub
Just Call above Function by passing your String as Parameter
MesageBox.Show(GetSubString("FR-0612-037320-CHARITY REF 006 0600051970001"))