What happens you delete a character in Animal Crossing New Leaf

If you created a new save file then the old one is gone. You can not recover it or restore it. Not even from a back up. If you did manage to have the old file backed up, the file will be considered invalid and the system will want to delete it and create a new game if you try to access the old file.

The following negative effects could happen (list adjusted to represent the 8 hour time travel backwards):

• More weeds (does not happen with Beautiful Town ordinance)
• Flowers will shrivel or die (does not happen with Beautiful Town ordinance)
• You could get Bed Hair
• Turnips will rot
• Cockroaches might appear in your character's house (does not happen with Beautiful Town ordinance)

Since you are only going 8 hours backwards, I doubt that there will be much weed or flowers that have died. The only effect that is guaranteed to happen is that the turnips will rot if you go back in time.

Sources:

Animal Crossing Wikia

Thonky.com