$ sudo apt-get remove grub-imageboot 

Uninstall grub-imageboot including dependent package

If you would like to remove grub-imageboot and it's dependent packages which are no longer needed from Ubuntu,

$ sudo apt-get remove --auto-remove grub-imageboot 

Use Purging grub-imageboot

If you use with purge options to grub-imageboot package all the configuration and dependent packages will be removed.

$ sudo apt-get purge grub-imageboot 

If you use purge options along with auto remove, will be removed everything regarding the package, It's really useful when you want to reinstall again.

$ sudo apt-get purge --auto-remove grub-imageboot 

See Also,