These are the options which I see when grub menu is loaded.
Are these Memory tests needed. What does Memory tests do? Can I remove them using grub customizer.
Memory test is for well... testing the RAM in your computer. Example if your system starts to behave oddly, crashes often or simple die. You can run memory test to see if the RAM have become faulty.
If I were you, I would keep those entries.
While it is possible to run a memory test in EFI/BIOS, it is handy to have those functions just in case.