An Azure relational database service.
When an Azure SQL logical server is deleted, it is soft deleted, which allows Azure support to restore it quickly in exceptional circumstances. Azure retains the server in this state for up to five days, which reserves the name for that period. If an attempt is made to create a server with the same name under the same subscription, then the old server is released immediately, and the name can be reused.
Please create a support ticket as soon as possible and do not reuse the name of the server, to see if Azure Support is able to recover the server for you. There is no guarantee, but they will make their best effort.
If you have other Azure SQL logical servers in use, please consider implementing resource locks to prevent accidental deletions from happening.
Hope this helps.