Technician wants remote access

I recently built my first PC. I downloaded and installed a free version of Windows 10 Pro. I waited until I had some extra cash and decided to buy Windows 10 Home as my OS. I was told by one technician, Home will override Pro. But it did not. I get an error (0x803F700). I found a troubleshoot that sounds exactly like the problem I would have. I have a digital license for Windows 10 Home, but Windows 10 Pro is installed. I tried following the troubleshoot, but no instructions pop up, as another set of instructions said it would. 

I called 800 642 7676. I got this number from Google, I even went into Microsoft Tech Support website and searched for correct numbers and found it there too. You think this would ease my mind, but it does not. Speaking to one rep (again, I called the number above), he said he had to do a remote access to help. I told him no, I will do it (I rather learn anyway).

He sent me an email, with the Media Creation Tool (which I told him I already have, but that is fine). It gave two options, which did not line up with what he said. He told me to pick one (ISO File Download) After the download, he gave two more options, again, did not line up with what is on my screen. I read everything on the pop up to be as clear as possible. 

Eventually he circled back around to remote access. I do not want to do that, I do not trust him, or anyone on the internet. He said "Its been 35 minutes, we can just do this if I remote access". Pressure does not help me. 

Do Microsoft Technicians remote access? If so what system do they use? I read about Team Viewer, but I hear there are problems. Is the number above correct? I thought a clean installation would be necessary, but every technician I spoke to says no, it is not. I built this PC to just play games, that is all. I hate this has to be such a headache. Any clarification would be grateful!