Download a new copy of Windows using the (Second option on linked page) to an 8GB (min) USB. Media Creation Tool
Boot that USB and choose a Custom Install.
Delete all UEFI partitions on the system drive (EFI System, Recovery, MSR Reserved, Primary).
Select the unallocated space that results...
First things first uninstall Norton using the official Norton uninstall tool as explained at this link, windows defender will then take care of all antivirus
https://support.norton.com/sp/en/us/home/current/solutions/v60392881
Best bet it's start your own post rather than hijack this one, and have a read of this
https://www.pcspecialist.co.uk/forums/threads/please-read-before-posting-collaboration-of-helpful-hints.77691/