Specially Record A Ubuntu "/boot/efi space too small" issue

Other than Ubuntu, the WD SN550 used to have APPLE MACOSX, Microsoft Windows,

after investigation, command used is "sudo du -m /boot/efi", found Microsoft and APPLE not needed, so, just do a clean up "sudo rm -rf /boot/efi/EFI/Microsoft && sudo rm -rf /boot/efi/EFI/APPLE",

the warning of disappears, also, for more kernels of Ubuntu, use "dpkg , for installed linux-image, uname -r, apt-get remove linux-image ..."