What happened is OP imported an AzureRM resource group into a terraform resource, then "deleted" the resource by changing to a data block. When you delete a resource group in AzureRM it deletes every resource under it. This behavior is pretty stupid when mixed with terraform but as a rule of thumb if I'm not importing every resource under a resource group into the state then I make it a data call from the start. The missing step was to `terraform state rm <addr>` on the resource group and then change it to a data block.