GRUB stands for GRand Unified Bootloader.
Typing the path to Windows is not as simple as you may think. A series of commands (Linux commands) are involved and you need to know the drive and partition where Windows is located. However, the fixmbr tool (I assumed that's what you used) simply replaces GRUB, so there is no need to type anything. Also, keeping GRUB if you don't have a Linux based OS is useless. This is an example on how to fix the issue:
https://askubuntu.com/questions/493826/grub-rescue-problem-after-deleting-ubuntu-partition
Which is a bit different because in this case the user had Ubuntu installed. The second answer actually describes the procedure you probably used, but if you are dual-booting, that would erase such possibility, which is why the first answer would be the correct one if you are.
As you can see, the problem usually starts when dual-booting and the partition that contains Ubuntu (or at least the one that contains the kernel) is deleted, so GRUB doesn't know what to do. Then you have to rescue it.
