Limiting the consecutive occurrence

[Pixel]

Hmm, right now I can think of anything for that, as far as I know there's nothing near to that in sed.

Can grep delete lines too? as you only need to delete any line that contained these.

Code:

ABCDEF
BCDEFG
CDEFGH
DEFGHI
EFGHIJ
FGHIJK
GHIJKL
HIJKLM
IJKLMN
JKLMNO
KLMNOP
LMNOPQ
MNOPQR
NOPQRS
OPQRST
PQRSTU
QRSTUV
RSTUVW
STUVWX
TUVWXY
UVWXYZ

Edit:
just thinking, what would be the likey hood that 8 upper alpha password would have ABCD or MNOP because if its unlikely which I would think, then I could tighten this up and remove any line with 4, 5 and 6 characters in a alphabetical order any where in the whole line. This would further reduce the lists.