@Juan Ramirez Thank you for reaching out to us and sorry for the delayed response.
AFAIK, it is still not possible to delete a MODERNIZED ASR DR appliance as per last update that we received from the SME.
Trying to get an update directly from the product owner. Shall update the thread once I hear back from them.
Thanks for your understanding!
EDIT: Confirmed by product team: Currently, this a feature in development stage. So, the solution/workaround is to delete the vault and complete resource group itself.
Sorry for the inconvenience this must have caused you!
If the response helped, do "Accept Answer" and up-vote it