Sorry for the confusion. I experienced the exact same problem yesterday with Advanced System Care as well. Other experts on the forums swear by it but I have never been able to get it to work. I assumed it was because of my protected network I am on. I always used CCleaner but I have heard so many times that ASC was better, and perhaps it is if it would ever download. Don't worry about that because I suppose their download is broken.
So, since you cannot use the tool to uninstall, the purpose was to clean out the registry in one step. Having an HP computer I cannot give you the full scrub steps so I want to make this as easy as possible for you. Hopefully this works because it can get redundant if not.
1. Uninstall the printer and all associated programs from Add/Remove Programs.
2. Download and run CCleaner instead (remember to click the green "Download Now" button under the word CCLEANER). Again, with 3rd party software it is at your own discretion and I nor HP are responsible for problems caused using it, but I like this cleaner personally and have not had any problems. Use it to the fullest of its abilities. Save a back up, clean everything it suggests, and please let me know if you have any questions.
3. Turn off the computer completely and then turn it back on - instead of just resetting the PC.
4. Install the Full Feature Software and Drivers and customizing the software that installs to make this time go by faster (I will post a picture of what I mean).
5. Try to scan.
This is a very easy step. If this does not work, let me know. Sometimes a simple uninstall/reinstall with a computer cleanup can fix it but other times it requires an even deeper clean than I have suggested in this step. I just want to set that expectation now but that I am more than happy to help you!