Hello @Anonymous ,
I understand that you were unable to delete a Virtual network and receiving the below error: "Error: Subnet blog-flaskAppSubnet is in use by flask_group/providers/Microsoft.Network/virtualNetworks/blog-flaskVnet/subnets/blog-flaskAppSubnet/serviceAssociationLinks/AppServiceLink'>blog-flaskVnet/blog-flaskAppSubnet/AppServiceLink and cannot be deleted".
You already tried the recommended steps, but it didn't help.
So, we created a support request to delete the AppServiceLink from the backend.
The support team engaged the backend tem and they deleted the Orphaned Service Association Link, post which you were able to delete the Vnet successfully.
Kindly let us know if the above helps or you need further assistance on this issue.
Please "Accept the answer" if the information helped you. This will help us and others in the community as well.