There's no such thing as a two dimentional array in Perl per say. That means you have to remove elements from multiple row arrays. That means you need a loop. Loop over every row, and splice the offending column from the referenced row array.

# Remove the 4th column.
splice(@$_, 3, 1)
   foreach @$rows;
[download]

Update: Two swap two columns, use splice to remove one, and use splice to reinsert it at the new location.

# Swap the 3rd and 4th columns.
splice(@$_, 2, 0, splice(@$_, 3, 1))
   foreach @$rows;
[download]

Alternatively, create a translation map and use an array slice:

# Swap the 3rd and 4th columns.
my @map = (0, 1, 3, 2, 4, 5);
@$_ = @$_[@map]
   foreach @$rows;
[download]