Lacking, or
irrelevant to,
moral concerns.
A person or creature is amoral if s/he does not think in terms of morality, or (for that matter) does not think at all.
An act is amoral if it is neither good nor evil.
Being amoral is not the same as being immoral; the latter specifically refers to violating some code of morality, whereas the former refers to ignorance or irrelevancy of morality.