Current wrong behavior
When the user tries to remove a vm from an existing plan and it's not allowed for some reason (i.e. last vm in a plan, plan status doesn't support vms removal etc), then the cancel virtual machines or remove virtual machines buttons are always enabled , but once clicking on them, an error modal with an alert is displayed.

This is a wrong behavior since it misleads the user to think that the operation is allowed.

Suggested behavior
Once the remove/cancel vms operation is not allowed, the remove virtual machines or cancel virtual machines buttons should be disabled and a tooltip next to the button should include the reason for the disabling.