Power Platform Admins are currently able to delete Flows, Apps and Environments via PowerShell or Power Automate. It is a really important feature for governance.
However as of today, there is not any "clean" way to properly delete a chatbot as an Admin. The only way currently available is to delete it via the PVA Portal.
It would be really interesting to be able to progamatically delete PVA Bots for Power Platform Admins, either via PowerShell, Power Automate or a REST API. One reason is that if a tenant license is purchased, the chat sessions will all count as billed sessions, even if they take place with Bots authored with a Trial. To be able to control the company costs, it is then importnant for Admins to be able to delete Bots issued from Trials if required to keep a reasonable amount of chat sessions.