Clean install windows 10 in uefi

[Spider 6]

I have an accer p246m m laptop which has an i3 4000 and hd 460
It was my sisters laptop and she was using dualboot with win 7 and 8
The charger broke and left it unused for 3 weeks
When i got it i tried to boot but no bootable device was shown so i searched internet and changed bios to legacy and it booted fine
Now there was some problem the windows 7 files were not found one drive was completely clear
And there was also screen flickering problems
Updated to win 10 not the latest then updated drivers small flickering still existed tried every solution

Now i wish to clean install windows 10 in uefi from legacy so how should i completely wipe the existing files and resest bios to clean install fresh windows 10 in uefi like in a laptop that came with bios only??

Sorry its pretty long i thought i should mention everything and i hope you understands?

 

[Colif]

Is this it? https://www.cnet.com/products/acer-travelmate-p246-m-33ph-14-core-i3-4030u-4-gb-ram-500-gb-hdd/

it has UEFI, if it lets you choose Legacy in the BIOS, it is a UEFI. Before EUFI there was only legacy anyway, its only called that now cause there is a choice.
you may not need to change anything in bios to clean install win 10 in UEFI mode, it should recognise that fact itself when you go to install win 10 and set BIOS up for UEFI boot
download the Windows 10 media creation tool and use it to make a win 10 installer on USB - so you have latest version, if you don't have it already
change boot order in BIOS so USB is first, hdd second
boot from installer
follow this guide: http://www.tenforums.com/tutorials/1950-windows-10-clean-install.html - step 13 shows what you need to do, delete all partitions and click next.

when you reach the screen asking for licence, click "I don't have a key" and win 10 will continue to install and reactivate once finished

On the screen where you choose where to install win 10, if it gives you an error about GPT drives, delete all the partitions on the hdd and press next. If it still gives error, cancel out of the installer and restart PC and start installer again, it will accept next on that screen this time (some PC just need a restart here)