"Windows doesn't find 'C:\Program Files (x86)\Arduino\uninstall.exe'. Check that you entered the correct name, and try again"
"Arduino version 1.8.5 is already installed and must be uninstalled before you install this version. This won't affect sketches or libraries in the sketch directory.Click 'OK' to uninstall from : C:\Program Files (x86)\ArduinoClick 'Cancel' if you have files in the install directory that you wish to keep (most users don't). Copy them somewhere else then re-run the installer."
@ctbruceStart with the clean up PDF's attached to the post above yours. Did thatClearly there is some form of security or policy in effect on your computer.You say you are the only admin but there are at least two levels of admin.A user with admin privileges is not the same as a full administrator.Some people also mistake being the only user of a computer as a user with admin rights which is a fallacy.
The file was downloaded from the Arduino site from the non-administrator download. I am able to download and once downloaded I can Delete that file no issues just this particular one Arduino 1.8.5 windows
Which file / folder in particular are you having issues with ( DETAILS ) ?