When you have multiple subscriptions, sometimes you create namespace in some another subscription rather than the one in which you exactly wanted to create. Some of the customers delete the namespace and try to create the namespace in correct subscription by same name, however creating namespace it gives error saying, the namespace name is previously used in another project and has been deleted less than one week.
This is due to 7-day grace period when a namespace is deleted. Service Bus doesn't allow someone to claim the namespace before 7 days from any other subscription.
This will get re-created immediately if it’s being created in the same subscription. If the deletion and re-creation is being done in two distinct subscription, then there is blocking period of 7 days and you need to wait for that.
To overcome this issue, you can follow the steps mentioned below:
You can move the Service Bus namespace from one subscription to another subscription.
Just make sure that the user is admin/owner for both source and destination subscriptions.
To move the resources from one subscription to another go to new Azure Portal(Ibiza) and re-create the namespace in the same subscription from which you have deleted it
Once Service bus namespace is created, select your Service Bus namespace, and go to Overview section, there under Essentials you will find an option of Subscription name (change) as shown in below image.
It will take some time to complete the move resource operation, finally it will show notification once it gets completed as shown below.
Note: Once you moved the resource to another subscription, please check in the destination Subscription and confirm if the resource is moved, as sometimes it ends up with failure error.
Hope it helps...