Tried:
# wipefs -a /dev/md127
which did not word, so I next tried:
# wipefs -f -a /dev/md127
/dev/md127: 6 bytes were erased at offset 0x00000000 (crypto_LUKS): 4c 55 4b 53 ba be
and then
# mdadm -S /dev/md127
mdadm: Cannot get exclusive access to /dev/md127:Perhaps a running process, mounted filesystem or active volume group?
but the filesystem is still mounted.
curious, that creating an encrypted raid system on fedora seems to be an irreversible action.