EDIT: I checked a bit deeper regarding this and yes, I was wrong regarding the deactivation of the account, still the same consequence as erasing the account, the games will be rendered unusable in the system(s) you deactivate your account from.
If by deactivate you mean that you're going to erase the account, then yes, every game you've got that was downloaded by that account will be disabled, that means you won't be able to use it any more since the "owner account" is not in your system any more.