Demoting Domain controller manually

 Certain situations, such as server crash or failure of the DCPROMO option, require manual removal of the DC from the system by cleaning up the servers metadata. The following detailed steps will help you accomplish this:

Removing metadata via Active Directory Users and Computers

1. Log in to DC server as Domain/Enterprise administrator and navigate to Server Manager > Tools > Active Directory Users and Computers
2. Expand the Domain > Domain Controllers
   
3. Right click on the Domain Controller you need to manually remove and click Delete
   
4. Click Yes to confirm within the Active Directory Domain Services dialog box
   
5. In next dialog box, select This Domain Controller is permanently offline and can no longer be demoted using the Active Directory Domain Services Installation Wizard (DCPROMO) and click Delete
   
6. If the domain controller is global catalog server, in next window click Yes to continue with deletion
7. If the domain controller holds any FSMO roles in next window, click Ok to move them to the domain controller which is available

Removing the DC server instance from the Active Directory Sites and Services

1. Go to Server manager > Tools > Active Directory Sites and Services
2. Expand the Sites and go to the server which need to remove
3. Right click on the server you which to remove and click Delete
   
4. Click Yes to confirm
   

Remove metadata via ntdsutil

1. Right Click on Start > Command Prompt (admin)
2. Type ntdsutil and enter
   
3. You are then presented with the metadata cleanup prompt
   
4. Next type remove selected server <servername>
   NOTE: Replace <servername> with domain Controller server you wish to remove
5. Click Yes to proceed when presented with the warning window
6. Execute the quit command twice to exit out of the console

Remove a Office 365 user from the Restricted users list

 https://security.microsoft.com/restrictedusers

Use the Microsoft 365 Defender portal to remove a user from the Restricted users list

In the Microsoft 365 Defender portal, go to (incidents & Alerts) Email & collaboration > Review > Restricted users.

On the Restricted users page, find and select the user that you want to unblock by clicking on the user.

Click the Unblock action that appears.

In the Unblock user flyout that appears, read the details about the restricted account. You should go through the recommendations to ensure you're taking the proper actions in case the account is compromised.

After you remove the user it needs 15 to 20 minutes to take effect.

When you're finished, click Next.

When you're finished, click Submit.

Click Yes to confirm the change.