Hello @Uday Kiran Reddy (ureddy) ,
In general when you create AKS cluster and delete the resource group , quotas will be restored immediately. I just did a quick test on my subscription by creating AKS cluster and deleting it immediately.
So please validate from your end if there are any resources being used in EastUS2 for DSv2 Family still.
From the error message , it clearly says that - 8 cores of dsv2 is still being used.
Location: eastus2, Current Limit: 10, Current Usage: 8, Additional Required: 6, (Minimum) New Limit Required: 14.
You can always validate your quotas https://firstname.lastname@example.org/resource/subscriptions/<subid>/quotas