If a bank wants to discontinue taking deposits at ATMs, what are the things to consider with regard to customer notices/disclosures as well as the contract with the ATM network provider?

You undoubtedly include ATM deposits as one of the types of EFTs that customers can initiate with their cards, in your account disclosures, and perhaps in collateral material you send with cards. You will need to update those if you are shutting down ATM deposit capability altogether. That means you need to also notify your existing cardholders of the change, because it means they have less EFT access.

Although the regulation doesn't require it, I also recommend posting a notice at each affected ATM for a couple of weeks before you drop the service.