Undo bcdedit set from uefi or ubuntu

I'm trying to install ubuntu in dual boot along with windows 10. I have two hard disks. Windows is already installed in disk0. Then I installed ubuntu 18.04 LTS in disk0 after windows. Both were working fine. But every time I restart, it used to load windows by default. To enable grub, I found the below command and executed in windows command prompt with administrator privilages

bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efi

After this, whenever I reboot, it opens Grub command line. If I go to bios/uefi, I can start ubuntu from there or I can select Windows Boot Manager. Ubuntu is working fine, but if I select Windows Boot Manager, again I get into Grub command line. So, I'm not able to boot windows at all.

How to fix this? I found a command to undo bcdedit

bcdedit /deletevalue {bootmgr} path \EFI\ubuntu\grubx64.efi

But to execute this, I need to be in windows right? So, I'm not able to execute this command. Is there a way to perform this action from bios/uefi (Asus computer) or from the ubuntu? (Ubuntu is booting fine)

Or is there any other method? I'm open to all suggestions.

Additional Info: Also, I installed grub2 and now I'm able to see grub bootloader after restart. Here, I get 2 options: ubuntu and windows (from sda2). If I select Ubuntu, ubuntu loads fine. But if I select windows, I get an error saying invalid signature

Edit 01: I ran boot-repair tool. The details are in this paste ubuntu