It looks like the kind of tab that you lift instead of push in.
Sometimes you can get a tiny jewelers screwdriver under the tab to hold it open while you try to pull on the relay.
I was curious so I went out and removed my fog light relay.
The whole relay and connector are on a metal tab. You just wobble and pull it straight down.
There is a plastic tab and you have to lift it up.
I used a dental pick.. They even sell them at auto parts stores. They come in really handy.