I tried using boot/fixmbr , /fixboot and all...! but still it is not yet removed....!

Insert Windows 8.1 Media (CD/DVD) in to the Optical Drive.

On the installation screen where it asks you to install windows, click on "Repair Your Computer"

Go to command prompt and type bootrec/fixmbr

This will help to remove GRUB and you can now boot into windows directly.

You may also go through the following article:

How to Uninstall a Linux Dual-Boot System From Your Computer

Hi knlar45676,

Would you please share us more details of this issue ?
Are you working with a dual boot system machine (Linux and Windows 8.1 )and now you want to remove the linux option from the boot option ?
If that is the issue ,please refer to the link as S.Sengupta suggested to have a check .

Best regards