And while M0 is usually the most stable, not only DOES cash get created and destroyed, this is even independent of loan/debit creation (which is another measure entirely).
Central banks may call in and destroy, convert, or give out cash to banks with and without changing loans/debits and so forth, for all sorts of considerations.
It's really not that simple.
But speaking of the official classifications, money is not conserved or constant, can be destroyed or created and change its relationship to other categories. Ex: https://3.bp.blogspot.com/-Dd1sW5ny2F0/Tb1e6oteMuI/AAAAAAAAB... Where M0 is cash, and M1 are funds directly available for payment and so forth.