How to remove devices from ZHA and re-add to Zigbee2mqtt

As above am i right in saying theres a config file somewhere i can edit…? ive tried removing them in the gui but the delete button has been greyed out…message says that the said device is still tied to a config or something like that but its not…

Scrub that…went back to try again to delete and was able to - no idea why i could do it now…cheers.