Cos to rmui
1. Flash COS TWRP (For rmui to cos use rmui twrp)
2. Move the files to SD Card.
3. Format data in TWRP.(wipe > bottom right > type yes)
4. Go to install page in TWRP.
5. Install the zip. (Do not Reboot)
6. Install stock rmui recovery as recovery (for rmui to cos flash cos stock recovery)
(if you skipped above step dont worry recovery included in zip)
7. Reboot to stock recovery
8. Wipe data & reboot.