I was investigating a problem concerning Adafruit_BusIO. (A message that no headers files (.h) found in it. I wasn't using it and haven't done so, at least recently. So, after an hour or so of fruitless inspection of the sketch invoking the message (despite running it OK), I went to Manage Libraries with the intention of removing it as my next step.
But there is no Uninstall, Delete etc option. The version shown as Installed was 1.9.6 so I used 'Select version', chose 1.9.5 and pressed the now accessible (bold) 'Install' button. But 1.9.6 remained installed. Repeating this a few times I found that the Install button greyed again if the mouse was briefly moved.
Q1. Is it a (minor) bug? Presumably install should not be offered at all for an already installed library)?
Q2. Is it impossible to remove a library via the IDE? Can you do it only by externally using File Explorer?
Q3: Is 'Previous versions' to be used only for trouble-shooting after manually uninstalling? Otherwise why would anyone want to install an older version?