HELP. 10 hours countdown. Do I need to complete the interrupted install of Win 10 before cleaning up my Win 7 OS?

I started the process of upgrading from Win 7 to Win 10 several times, beginning months ago. Meanwhile Microsoft kept downloading files to prep my system for the install I had reserved. After several failed installation, this morning finally win 10 began to install successfully, but here we are at 85% and I suddenly decide that I do not want to upgrade. Accidentally I am reading an article talking about all the undisclosed issues about win 10 and suddenly all the glitches that I had been experiencing made sense. In addition, the article points out the fact that win 10 meets all the criteria for spyware. In many ways I have to agree, particularly when (according to this article writer, and confirmed by a reliable source) it does not allow to choose when or what window will update. It may also not be as friendly to the download of third party programs, but worse of all it actually requires permission to access photos, documents, etc. Some may not care much about privacy, but I do. I also did not know that it is not quite as easy to do a safe boot as just pressing F8 or that DVD playback support is gone so the ability to play a DVD for those who still do so will no longer be there. Apparently the ads on the screen are there for the laptop as well, not just phones. Having a laptop, memory and wi-fi time are very important factors and I feel bad for those who pay for wi-fi use without even knowing it because of the unknown updates taking place regardless on how they are connected. I guess they would have to shut down their computer all the time when not using it to avoid that problem and then suffer through slowing down. Since I travel to Europe that alone would be enough to make me pass.
So, please, help me. I do not know how much of win 10 has already replaced my original win 7 and if I can still use system restore or worse but necessary do a complete system repair or restore.. I do not know if I can do so that now or do I have to complete the win 10 installation and then do it? I have no idea what happens when installations such as these dump so many files over time, then they begin successfully, but are forcefully interrupted. Confusion reigns and my registry is messed up royally. I am writing from my old MAC for fear of turning on the PC. Thank you. I love this site and it has helped me tremendously. You guys are fantastic, especially when taking the time to show the screens and go step by step for those of us who are fed up with the 3 hours useless calls to *** techs who know less than we do. I feel terrible for those who are afraid of even opening files, especially the elderly who squander so much money on those calls. In my little way I try to help others whenever I can, for free of course, as I give joyfully what I myself am learning freely from so many nice people. Thank you again.