Here is a copy of my
earlier response in the RCU thread in case others see only this one:
In the meantime, this error simply states that your computer is failing to remove the existing version, and until it does, obviously it won't let you overwrite it with the new version. This could be a permission issue, and I see you've tried running as an administrator. However even an administrator doesn't have permission to overwrite a file that the administrator has open. Perhaps you have the exe running under another login, or else Windows thinks you do. Rebooting will fix this. Are you able to rename OPConfig.exe to something else like OPConfig.old? If so the installer should work.
You may want to try uninstalling the existing version yourself (rather than letting the auto-installer do it), by going to Programs and Features, select OP Config from the list, and uninstall. Then download the new version of OP Config from the downloads page and install it manually (by double-clicking the exe). The auto-installer that you can launch from within OP Config needs to close OP Config before it can complete the installation procedure, but perhaps it isn't running with sufficient privileges to do so.
There may be other things we can check but like I say, if this doesn't resolve it please start a thread in the Open Panzer forums.
Now to respond specifically to your post here - your attempt #3 should not happen since of course there is no file to delete, you have already removed the program. The fact you are getting the third error that says it can't rename a file in the installation directory, when that directory doesn't even exist, suggests an issue outside of OP Config.
If you Google this you will find many instances of people encountering this problem for various softwares. The issue almost always has to do with an antivirus program, such as McAfee, BitDefender or others that are blocking the installation. Do you have any of these programs installed and running? If so I would disable them and try the install again. If you are running McAfee
see this post for a possible solution.
It may be possible to provide a Zip install, I have not considered that before. Let me explore it further. Some things would not work such as file associations but that may not be a big deal. I will have to think about it, in the meantime let's try solving this issue.
Luke