If you have, as an example, a 3x3 matrix:
A = { {1, 2, 3}, {4, 5, 6}, {7, 8, 9} }
Such that Ax = 0
and you perform row reductions on it
and at a certain point it reduces to:
{ {1, 2, 3}, { 0, 1, 2}, {0, 1, 2} }
Then you could legitimately remove
one of {0, 1, 2} from the system...