dual boot - Remove MacOS partition from macbook pro retina dualboot with ubuntu mate 16.04

I would like to remove the MacOS partition from my macbook pro retina since I'm not using it more.

I know how to remove a partition using gparted, but I'm using refind, installed through MacOS, as bootloader. I'm not sure if I can reboot after deleting MacOS.

This is the output of boot-info, maybe can be usefull.

http://paste2.org/91XWkKGG