Before getting into registering you account, it's important to make a distinction on the different types of accounts an IoTeX Delegate owns: a Profile Account, an Operator Account, and a Rewards Account. These are not necessarily three different accounts.
This is the main, and most important, of all three accounts for a Delegate. The Profile Account is used to register the Delegate in the network, manage its configuration, and set the Operator and Rewards accounts addresses. Because this is the most important account, you may want to generate it using a hardware wallet - such as the Ledger or Trezor wallets.
This account is used for the actual node software running on your node servers (check out High Availabilityto learn how to run backup nodes that share the same Operator Account). We advise using an Operator Account that is different from the Profile Account, to avoid exposing your Profile Account to the node operator if it's managed by a third party, or to hackers that could get access to your node configuration on the server. Because the private key must be included in the node configuration file, you cannot use a hardware wallet for your Operator Account.
If your Operator Account's private key gets lost or exposed, you can just use a different address as long as you also change it in your Delegate profile.
This is the last account to configure for a Delegate profile. The Rewards Account receives the Delegate rewards when you claim them. Depending on your needs, the Rewards Account can match the Profile Account, the Operator Account, or it can be its own account.
Since claiming your Delegate rewards requires using the ioctl command-line client, you cannot use a hardware wallet for your Rewards Account, because the command-line tool does not support hardware wallets.
If your Rewards Account's private key gets lost or exposed, you can just use a different address as well as you also change it in your Delegate profile.