While you could remove the server from that point, it will not actually remove it from the domain.

If the server is dead and you want to use the same name, then do a disaster recovery installation on a new build with the same name. If you want to change the roles you could then remove the server correctly using add/remove programs.

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ADSI Edit, navigate to:
(ADSIEDIT.msc (Active Directory Service Interfaces Editor))

Configuration > Services > Microsoft Exchange > Administrative Groups > Exchange Administrative Group (FYDIBOHF23SPDLT) > Servers