Well, I was fighting with this minor issue for almost a week now and as soon as I open a discussion about it, I’ll find the answer accidentally myself …

This is what I did:

• Log in to vROps Portal
• Go to Administration --> Inventory Explorer
• In the Tree-View, make sure you deselect everything (hitting the “Deselect All” Icon above it)
• Look for the Host on the right Pane (you can use the search in the upper right corner of the pane)
• Select it, and hit Delete Object (Red cross on top of right pane)

There might be multiple items related to a Host (e.g. localstorage,…)

My mistake before was, that I went to Inventory browser --> Host System (within the Tree View). There I could choose the actual ESXi Host, but the Delete Object Icon was greyed out.