Hello @Heiler Matos , Welcome to the Microsoft Q&A forum.
As I understand from the question above you are unable to delete an Azure Virtual WAN instance via Portal even though it does not have any dependencies.
Can you try deleting the resource via PowerShell as it will give us more insight on why you are unable to delete the resource. You can run this command Remove-AzVirtualWan to delete an Azure VWAN instance. If you do not have PowerShell set-up in your local machine you can run this command via Azure Cloud Shell. For example when I tried deleting a VWAN instance (In my case there were dependencies) I got an error in below format, which provides more insights.
Hope this helps! Please let me know if you are still unable to delete the VWAN instance. Thank you!