#スロット番号を指定して削除
$ cryptsetup luksKillSlot /dev/sda1 0
Enter LUKS passphrase

#特定の鍵ファイルやパスフレーズを指定して削除
$ cryptsetup luksRemoveKey /dev/sda1
Enter passphrase to be deleted: #削除するパスフレーズを入力

$cryptsetup luksRemoveKey -d /etc/sample.key /dev/sda1

$ cryptsetup luksDump /dev/sda1
LUKS header information for /dev/sda1

Version:        1
Cipher name:    aes
Cipher mode:    xts-plain64
Hash spec:      sha256
Payload offset: 4096
MK bits:        512
MK digest:      18 02 4b 66 1e 61 fd 99 a8 a5 e5 60 2d 66 4b 6c 65 ea 1e 68 
MK salt:        ba be 36 05 f9 49 79 91 9f 02 0c 56 d0 1f 25 2a 
                f8 2c 6b c0 7a 4f 3f a9 e0 b8 d9 18 f4 b8 67 0c 
MK iterations:  13170
UUID:           71b0a1bd-f08e-45df-8371-dbaf69eaf834

Key Slot 0: DISABLED
Key Slot 1: ENABLED
        Iterations:             211406
        Salt:                   1a b5 75 1f 84 9a 2e 6d a6 c0 15 aa b8 69 e1 23 
                                d2 cb 90 c5 d3 64 26 dd f7 83 3c 65 c8 3b b0 07 
        Key material offset:    512
        AF stripes:             4000
Key Slot 2: DISABLED
Key Slot 3: DISABLED
Key Slot 4: DISABLED
Key Slot 5: DISABLED
Key Slot 6: DISABLED
Key Slot 7: DISABLED
