How I can delete a group I have been created? ( I want to test this feature so I create a group but I can't delete my group now :( )

Hello everyone :D
I had submitted this code for "Preface Numbering" problem on usaco.
usaco says :

----- our output ---------
I_1400
V_500
X_1500
L_500
C_1500
D_500
M_101
---- your output ---------
I_1400
V_500
X_1500
L_500
C_1500
D_501
M_100
------ Data for Run 5 [length=5 bytes] ------
1000

But when I run my code in my computer my answer is equal to the usaco answer's. What's the problem?
Here is my code : http://paste.ubuntu.com/9743266/