memory which stores your firmware, i would sure hope that it is located on your keyboards pcb.
if you don't like the leds just remove the led drivers from you qmk config, that also reduces firmware size.
to do so, remove the blocks 'backlight', 'ws2812' and 'rgblight' from the keyboard.json. as mentioned before, ensure that each line, that is followed by another line in the same block (within the same braces '{}') ends with a comma. the last line of each block (the one before a closing brace '}') must not end with a comma. note that blocks can be nested and follow the same principle, if there are further statements (lines or blocks) on the same level, follow your block with a comma ( { block }, )
if you follow these rules and don't introduce typos, qmk should not complain about syntax errors