o365 and exchnage online sync issue

Question

i deleted some contacts from azure ad / o365 because these contacts are now being created as actual users in the tenant org. However when I go to add the alias (as was previously the contact) i get this error

This email address is already in use by an active ‎CONTACT‎ (‎Brian X(Brian.X@keyman .ca)‎). Try a different email.

There is nothing in deleted items in the tenant org.
I search for that email and it does not find anything .
i tried adding alias thru powershell got this :

PS C:\> Set-Mailbox "Brian.X@keyman .onmicrosoft.com" -EmailAddresses @{Add='Brian.X@keyman .ca'}
An Azure Active Directory call was made to keep object in sync between Azure Active Directory and Exchange Online. However, it
failed. Detailed error message:
Another object with the same value for property EmailAddresses already exists. RequestId : 06cf9225-9596-46c6-92b6-3da52cf264e9
The issue may be transient and please retry a couple of minutes later. If issue persists, please see exception members for more
information.

• CategoryInfo : NotSpecified: (:) [Set-Mailbox], UnableToWriteToAadException
• FullyQualifiedErrorId : [Server=YTBPR01MB3183,RequestId=42ad9568-09eb-4cd1-a937-5f1e20120f66,TimeStamp=2021-05-15 1:52:47 AM]
  [FailureCategory=Cmdlet-UnableToWriteToAadException] 5BE458BC,Microsoft.Exchange.Management.RecipientTasks.SetMailbox
• PSComputerName : outlook.office365.com

help help help

Answer 1

fixed my own

ran this cmdlt
Get-MsolContact -SearchString "* Email address is removed for privacy *" | fl ObjectID

then

Remove-MsolContact -ObjectId 40c4ca1a-4e15-40ad-b0bd-abeca4bcafcd -Force