I was going to uninstall the iOS module because I was running out of space on my drive and I saw the “Uninstall” button and without even thinking, I clicked it and Unity started uninstalling. So now I have to wait for it to install again. 
Good point, thank you !
Just a heads up, this just happened to me in Unity Hub 2.2.2 when I went to ‘Add Modules’ and accidentally clicked ‘Uninstall’. I’ve updated to 2.3.0 now and can’t see anything in the changelog stating that an uninstall confirmation has been added.
Hi again ! The hub team has a very big backlog of bugs to address and feature requests, this feature may not be in the 2.3.0 version of the hub but it will surely be implemented in future versions. We are trying to address tickets by their priority. We are very sorry for the inconvenience.