As you know, identity management is an important part of controlling access to resources and applications by end-users, especially when working with cloud services.
While Entra ID has quite few features to help in managing identities, these features are sometime limited to cloud-based only account; they can’t help in managing synced/on-premises identities, as as you know user state is control by Active Directory.
Well, good news as now you can use Entra ID Lifecycle workflow to manage (enable, disable, delete) your synced identities.
To do so, you first need to ensure you meet the licensing requirements (Microsoft Entra ID Governance licensing fundamentals – Microsoft Entra ID Governance | Microsoft Learn) – in this case Microsoft Entra ID Governance license (if need you can trial it https://go.microsoft.com/fwlink/?linkid=2252711).
Then logon to your Entra ID portal (https://entra.microsoft.com/) as at least Lifecycle Workflows administrator to access the Identity governance\Lifecycle workflows blade.
From there create (or edit) a workflow
Then create or edit the task related to the management state (enable, disable, delete) and enable to corresponding on-premise account option