Need help removing second not working windows installation

  arch, linux, windows

So basically i had a dual boot of windows 10 and ubuntu. only very rarely used ubuntu.
now i want to install arch linux instead of ubuntu, but i am afraid that i f-ed up the install with ubuntu already and if i delete it i will kill my working windows. also if i start i get a screen where i can choose between two seemingly seperate windows installations. It is a screen that looks like when you go on the "Advanced Options for Startup". (Will include a picture when im home from work). I usually ignore it bc it starts my "Windows 2" which works, automatically after 5 seconds. But there is also a "Windows" which doesnt work at all. I think it is there because i reinstalled my windows a couple of weeks ago ( which i do all 6 months because i need to declutter.) since then "two windows" are on my desktop. I am very competent with tech but i dont have much time to read into mbr gpt and stuff myself very much, so i would love to hear some tips how i can identify those two operating systems i want to remove, and remove them correctly. and also if someone were to tell me what i need to look out for if i want to install arch would be much apreciated
thanks in advance ppls

Source: Windows Questions