we erased the disk signature as the following ( this is after we performed umount )
wipefs -a /dev/sde
/dev/sde: 2 bytes were erased at offset 0x00000438 (ext4): 53 ef
then we check that disk is without file system as the following
lsblk -f
sde ext4 20eba791-c9c9-4462-aa23-74c40a41b8a0
but in spite we erase the filesystem , lsblk still show the ext4 filesystem on sde disk