See Soft Deleted Accounts in AzureAD | Restore Soft Deleted Accounts in AzureAD

See Soft Deleted Accounts in AzureAD | Restore Soft Deleted Accounts in AzureAD

To see all the accounts in AzureAD:
Get-MsolUser -All $true
Get-AzureADUser -All $true

To see all the "Guest" accounts in AzureAD:
Get-MsolUser -All $true | ? {$_.UserType -eq "Guest"}
Get-AzureADUser -All $true |where {$_.UserType -eq 'Guest'}

To get the details:
Get-AzureADUser -All $true |where {$_.UserType -eq 'Guest'} |select objectid,userprincipalname

This will return the userprincicpal names of the guest accounts. Usually in the format of:
accountname_domainoutside.com#EXT#@tenant-name-internal.onmicrosoft.com

If you delete a "guest" user or "member" user, the account is "soft-deleted" and is still in AAD. The account will be in this state of 30 days until the account is permanently deleted:
Remove-MsolUser -UserPrincipalName This email address is being protected from spambots. You need JavaScript enabled to view it.
Remove-AzureADUser -ObjectID This email address is being protected from spambots. You need JavaScript enabled to view it.

While the account is in this state, the account can be restored. However, the account cannot be added/invited to another Team.

To view account in the state of "soft-deleted":
Get-MsolUser -All -ReturnDeletedUsers
Get-AzureADMSDeletedDirectoryObject -Id aa644285-eb75-4389-886e-7233f096984c
This doesn't help much because we don't know the ObjectId. The only way I could find the ID is by looking at the AAD logs and filter for "Delete User".

To look at the logs, the AzureADPreview module must be installed:
Install-module AzureADPreview

After the AzureADPreview module is installed, run the following to check the logs for user deletion:
Get-AzureADAuditDirectoryLogs -Filter "category eq 'UserManagement' and OperationType eq 'Delete'" |ft
(The "Correlation ID" is the one you want.)

To permanently delete/hard-delete a guest:
Remove-MsolUser -UserPrincipalName This email address is being protected from spambots. You need JavaScript enabled to view it. -RemoveFromRecycleBin
Remove-AzureADMSDeletedDirectoryObject -Id aa644285-eb75-4389-886e-7233f096984c

To restore an account:
Restore-MsolUser -UserPrincipalName This email address is being protected from spambots. You need JavaScript enabled to view it.
Restore-AzureADMSDeletedDirectoryObject -Id aa644285-eb75-4389-886e-7233f096984c

NOTES:
Get-AzureADMSDeletedUser/Restore-AzureADMSDeletedDirectoryObject does not exist, yet.
AzureAD Module v2.0 documentation: https://docs.microsoft.com/en-us/powershell/module/AzureAD/?view=azureadps-2.0
AzureAD v2.0-preview documentation: https://docs.microsoft.com/en-us/powershell/module/AzureAD/?view=azureadps-2.0-preview
(Check out the difference in the documentation for "Deleted Objects" section to get a feel of where development is happening.)