The short answer is that this functionality has not yet been
implemented.
* If you're using the module provided by Opsview, then posting a
feature request on their forums *might* get some attention...
* If you're using the cparedes fork of the module (http://
forge.puppetlabs.com/cparedes/puppet_opsview) then submitting an issue
(or a pull request) to the github page will likely get some attention.
* If you're using the module that I posted to the Opsview forums a
while back, then you should really look at switching over to cparedes'
fork - it's much nicer.
Fwiw, implementing "ensure => absent" for the providers is something
I've been wanting to do, but I haven't had enough justification to
spend the time doing it yet.
-devon