You might even try the following function to manipulate the returning string
from OpenDialog box, though it's a bit clumsy, and obviouly not the best way.
function strPro(s:string) : string;
var
i : integer;
pos : integer;
len : integer;
begin
s :=trim(s);
len :=length(s);
i :=len;
while i>0do
begin
if copy(s,i,1)='/' then
begin
pos:=i;
i:=1;
end;
i:=i-1;
end;
s:=copy(s,pos+1,len-pos);
result:=s;
end;
procedure TForm1.btnGoClick(Sender: TObject);
var
s : string;
i : integer;
p : integer;
l : integer;
begin
openDialog1.Execute;
s:=openDialog1.FileName;
s := strPro(s);
label1.Caption:=s;
end;