Doesn't let me update it

It's referring to the internal memory not sd memory .Updates need to be installed in the system which is on the internal memory Try moving some of your apps from the internal memory to the sd to free up space on the internal storage . you can also move music and photos to the sd card . Once you move them make sure to go back and delete whatever you just copied over otherwise your not actually making space your just backing up. Once you made room you'll have no problem doing updates. Hope this helps