1) Remove all entries for that repo in private/etc/apt/sources.list.d
2) Remove all entries for that repo in var/lib/apt/lists
3) Remove all entries for that repo in var/lib/apt/lists/partial
4) Respring iDevice
5) Reboot iDevice



TIP: REPLACE [] WITH STANDARD HYPERTEXT PROTOCOL.
TIP: REPLACE WHATEVER IS BETWEEN THE [] WITH YOUR INFORMATION.



Hope that helps!