→ dpkg -r grub-pc-bin grub-pc grub2-common grub-common grub-gfxpayload-lists grub2
dpkg: dependency problems prevent removal of grub-common:           
 os-prober depends on grub-common.                                  

dpkg: error processing package grub-common (--remove):              
 dependency problems - not removing                                 
(Reading database ... 46021 files and directories currently installed.)           
Removing grub2 (2.02~beta2-36ubuntu3.12) ...                        
Removing grub-gfxpayload-lists (0.7) ...                            
Removing grub-pc (2.02~beta2-36ubuntu3.12) ...                      
Removing grub2-common (2.02~beta2-36ubuntu3.12) ...                 
Removing grub-pc-bin (2.02~beta2-36ubuntu3.12) ...                  
Processing triggers for man-db (2.7.5-1) ...                        
Processing triggers for install-info (6.1.0.dfsg.1-5) ...           
Errors were encountered while processing:                           
 grub-common