The easy way is to install grub-customizer tool:
sudo add-apt-repository ppa:danielrichter2007/grub-customizer sudo apt-get update sudo apt-get install grub-customizer When Grub Customizer starts up, you’ll see a list of all the items that show up in the boot menu. To hide entries that you don’t want to see anymore, simply uncheck the checkbox next to them.
But also, you can do it manually, see link.
For Fedora 20:
sudo wget http://download.opensuse.org/repositories/home:/Kenzy:/packages/Fedora_20/home:Kenzy:packages.repo -O /etc/yum.repos.d/home:Kenzy:packages.repo sudo yum update sudo yum install grub-customizer
For Fedora 23+ :
sudo dnf install grub-customizer