Removing final Exchange server, unable to follow Microsoft instructions

I'm reviewing the process to remove the last Exchange server in an environment by following Microsoft's instructions at https://learn.microsoft.com/en-us/exchange/manage-hybrid-exchange-recipients-with-management-tools#permanently-shutting-down-your-last-exchange-server. Step 5 of "Permanently shutting down your last Exchange Server" is to remove the service principal credentials created for OAuth. It provides some PowerShell commands to determine and delete the credentials:

5a. Run these commands in the Exchange Management Shell to get the OAuth credValue:

$thumbprint = (Get-AuthConfig).CurrentCertificateThumbprint
$oAuthCert = (dir Cert:\LocalMachine\My) | where {$_.Thumbprint -match $thumbprint}
$certType = [System.Security.Cryptography.X509Certificates.X509ContentType]::Cert
$certBytes = $oAuthCert.Export($certType)
$credValue = [System.Convert]::ToBase64String($certBytes)

5b. Find the KeyId that is same as the $credValue found above, run the following commands as a tenant admin using Microsoft Graph PowerShell.

Import-Module Microsoft.Graph.Applications
Connect-MgGraph -Scopes "Application.Read.All"
$ServiceName = "00000002-0000-0ff1-ce00-000000000000"
$p = Get-MgServicePrincipalByAppId -AppId $ServiceName
$keyId = (Get-MgServicePrincipal -ServicePrincipalId $p.Id).KeyCredentials $true | ?{$_.Value -eq $credValue}).KeyId

This gives the KeyId of the key whose value matches the $credValue found above.

5c. To remove the service principal credential, run the following command:

Import-Module Microsoft.Graph.Applications
$params = @{
  KeyId = $keyId
}
Remove-MgServicePrincipalKey -ServicePrincipalId $p.Id -BodyParameter $params

That last $keyId assignment in 5b is not a valid PowerShell command, there is a "$true" that is out of place and there is an extra ending parenthesis. It looks like the command got corrupted. Running Get-MgServicePrincipal manually does return a KeyCredentials object but I don't see a "Value" property that it appears to be looking for. This might just be because part of the command is missing.

Does anyone know how I can complete this step? Either thru working PowerShell or other method such as the M365 portal? Also would skipping this step also be ok, understanding it may leave crud behind?