It’s a skin for something that is not available yet.
Don’t worry, when you double-clicked it, you simply added it to a skin collection for something that will be unlocked with the release of HoT, so it wasn’t destroyed.
The glider will be part of the mastery system coming with HoT, which will allow you to glide through the new maps that come with the expansion. You will be able to change the appearance of your glider, which is what that skin is.