Simple answer:
s{/}{}g;
Fancy answer:
s{(\d+)/(\d+)/(\d+)}
{sprintf "%02d%02d%d", $1, $2, ($3 > 99)? $3: (($3 < 70)? ($3 + 2000): ($3 + 1900))}e;
which will turn 7/4/76 into 07041976 and 9/11/01 into 09112001. (As shown, '70 through '99 is converted to 1970 through 1999, while '00 through '69 is converted to 2000 through 2069.)