The Linux Systems are all booted by Grub. If you don’t have more than one operating systems installon on your system anymore, you can hide your grub, but not remove/uninstall it, unless you want to break your Linux System.
This is how you hide the grub from the boot sequence:
1. Open the /etc/default/grub (as root, or with sudo) in a text editor:
$ sudo vim /etc/default/grub
2. Set the GRUB_TIMEOUT to zero (GRUB_TIMEOUT=0)
3. Save the file and update the GRUB:
$ sudo update-grub
If you need to change to Recovery mode, press ESC when the Linux system starts (press ESC in the time between the BIOS initializing stuff and the OS start). If you press ESC in the right moment, you will get the GRUB menu and have the change to select the recovery mode.