Hi @Kei Moon ,
I would recommend a Hub&Spoke network topology for your requirement:
Hub vNet with AADDS and Spoke vNets peered with the Hub vNet
https://learn.microsoft.com/en-us/azure/architecture/reference-architectures/hybrid-networking/hub-spoke?tabs=cli
If you delete the AADDS everything is "gone":
Deletion is permanent and can't be reversed.
When you delete a managed domain, the following steps occur:
Domain controllers for the managed domain are de-provisioned and removed from the virtual network.
Data on the managed domain is deleted permanently. This data includes custom OUs, GPOs, custom DNS records, service principals, GMSAs, etc. that you created.
Machines joined to the managed domain lose their trust relationship with the domain and need to be unjoined from the domain.
You can't sign in to these machines using corporate AD credentials. Instead, you must use the local administrator credentials for the machine.
Source: https://learn.microsoft.com/en-us/azure/active-directory-domain-services/delete-aadds
If you create a new AADDS with the same name you start with an "empty" AD.