What is removed when uninstalling Skyrim? I'm having some issues with wierd things like mammoths and netches appearing in my vicinity sometimes out of thin air and immediately going after me. It has even happened in interior cells. At the worst it even happened in a new game during the waggon ride. I got attacked by a herd of mammoths that overturned the waggon. I eventually after restarting a number of times managed to get through Helgen with no mammoths but they still occasionally appear. I've been using the console to "kill" them but I'd like to stop it entirely.

When you uninstall the game does it remove your savegames? And your mod collection? Is there any other steps I should take?

Uninstalling Skyrim will not remove your mods, their files will still be there in the game's folder, along with nay non-Vanilla files like SKSE or ENBs, loose file replacers etc. Also, it will not remove Steam Workshop mod subscriptions. It shouldn't remove the saves and game settings either.

If you want do do a clean reinstall, you need to also wipe the game's folder and preferably the configuration (Skyrim.ini nd SkyrimPrefs.ini) files in Documents\My Games\Skyrim folder.