Delete a channel created by a user no more in the company

Hello, 

 

I would like to know what can be done to help a global admin delete a Stream channel that was created by a user that is no more in the company. My customer tried to delete a channel (he says it is a company wide channel), but when he tries he receive the message as followed: ««The authenticated user is not authorized to access this resource». 

 

If deleting the channel by the admin center of Stream, is there any PowerShell script that allows the deletion of a channel?