Linux present in boot menu(BIOS) even after deleting its partition from disk management ?
If this is the problem you have been facing quite sometime and not been able to find a solution , then you have reached the correct place to solve it in a safe and quite an easy manner.
Why do you still find Linux (earlier dual booted with Windows) in your boot menu even after successfully deleting its partition in the disk management ?
Because, the GRUB bootloader is still present in your PC’s EFI partition.
To solve this issue -
Step 1: Open CMD(Command Prompt) as administrator.
Step 2: Type “diskpart” .
Step 3: Type “list disk” to see the EFI partitions in your computer.
Step 4: Type “select disk 0” (Disk 0 is the single physical drive you have in your system, a 1TB HDD where your Windows is installed.)
Step 5: Type “list partition” to identify the EFI “system” partition.
Step 6: Type “select partition 1” (As in my computer “system” partition number was 1, so in your case type the number accordingly).
Step 7: Type “assign letter=x” (You will find around 126 mb allocated in windows explorer under drive ‘x’).
Step 8: Type “exit” to come out of “diskpart”.
Step 9: Type “x:”
Step 10: Type “dir’’ (you will find contents of your EFI system partition).
Step 11: Change your directory by typing “cd efi”.
Step 12: Type “dir” then press enter(you will find a folder named as your previously installed Linux version , which you are about to completely delete now ).
Step 13: Type “rd …/s” . (Put the name of your Linux folder which you want to delete in place of “…” , e.g: rd ubuntu/s).
Step 14: Type ‘Y’ to conform the deletion.
Step 15: Type “dir” to check if the required Linux folder was deleted.
The drive ‘x’ which was allocated earlier will itself get dismounted after a few fresh boot up’s. So, you don't need to format it explicitly .Even if you try formatting it, the Windows OS won’t give you the permission to do so.
Just saved you some precious hours of Googling ! :-)