I installed Kali as a dual boot with Win10, and cant change back to Win10

So here's what happened,
I decided to make a dual boot system for kali linux on my windows 10 pc. following the steps provided by a youtube tutorial, i successfully made a partition on my 2nd hard drive, installed the image on a boot drive and got it to work. However, after resetting the system, messing with the BIOS for over an hour and googling every solution, I'm still nowhere. I believe the part of the setup where i had to set the install location for grub must have been on the wrong hard drive, and now (despite all my windows programs still being on the hard drive) I cant load windows. I have given up and am even considering deleting Kali (or even everything) off of my computer and starting again fresh. Is there some way that i dont know of that i can go into the bios and change the default os from being Kali Linux? if not, is there a way i can delete all of Kali or factory reset my computer (to a point without any os) from within kali itself?
If at all possible i would be looking to keep the windows files as i dont have a spare copy of windows lying around

Thanks

-ps i know this is horribly phrased and written but i have been awake for about 20+ hours trying to figure this out.

Grub bootloader allows you to boot windows 10. Is your system type UEFI? You can go to boot options using F8/F9/F10/F12 (depends on the brand). In boot options there must be entries of both windows OS and kali.
You said you made a partition on 2nd hard drive. Does that mean that you were installing kali on that hard drive which is different from where there is your windows 10 present. For me dual-boot is both OS in a single hard disk with separate partition.
By default grub is installed in EFI partition along side with windows bootloader.
When you sucessfully installed kali-linux. What wrong you did which is now preventing windows 10 to boot?What happens when you try to boot windows? Windows 10 doesn't boot on Legacy BIOS if the windows partition table is GPT. Your Legacy BIOS must be disabled.
Tutorials you watch on youtube are bit old and what they show is not necessary that it'll work for you. Dual-booting kali-linux with windows 10 in UEFI firmware is a bit different. Legacy BIOS and Secure BOOT should be disabled no matter what you see on youtube.