I have a number of test vagrant boxes on my system which I am tidying up. I installed plugins eg like vagrant plugin install vagrant-hostsupdaterand vagrant plugin install vagrant-triggers. When I do vagrant destroy does that look get rid of the plugins while doing the destroy or not. I am deleting the directory after doing vagrant destroyso if not then how do I uninstall the plugins now that the directory has been deleted.
vagrant destroy does not remove plugins. As per https://docs.vagrantup.com/v2/cli/destroy.html, it "stops the running machine Vagrant is managing and destroys all resources that were created during the machine creation process".
You can uninstall plugins with vagrant plugin uninstall <name> (documented at https://docs.vagrantup.com/v2/cli/plugin.html)