I'm taking a significant performance hit with these textures with little or nothing to show for it. I'd really like to uninstall the thing. Is there a step by step for uninstall?

Just disable the HighResTexturePack01.esp and HighResTexturePack02.esp from from the Data Files from the game launcher.

Don't have it installed but from what I've heard it seems the texture pack is 2 esp files (actually blank) and 2 BSA files (the actual file that contains the hi res textures) -- so to uninstall them first go into the data options and uncheck the 2 esp files -- load the game and you'll most likely get the generic Save relies on some other content type prompt -- answer yes to continue - once the game loads make a new save and exit (this clears out the textures from the save file by creating a save that does not have the 2 esp files loaded) -- now go into your game install folder and in the data folder find and delete the 2 esp files and the 2 BSA files with the same name as the esps (or beginning with the same naming - since thie entire reason for having the esps is to get the BSA file to be used instead of the original textures) -- After deleting those 4 things you have uninstalled the HD texture pack from your game)

deleteing the BSA's will result in steam redownloading them.... as they are part of the game now... you can't disable/remove DLC connect that is connected to the game.

You can however of course disable them by unchecking them in the data files portion of the launcher.