Growing my own brussels- help please

let the leaves yellow then remove

Commercial growers remove them to accelerate growth of the sprouts but it's not really necessary as you could end up with a glut of too many ready all at once. I would leave them until any leaves start to yellow and then remove them. Make sure any dead leaves are removed from the ground as they are a good hiding place for slugs who love to climb up the stems and eat the tops off the sprouts. If you do want to accelerate the growth remove the bottom leaves but ensure the larger ones at the top of the plants are left in place (top third or so).

me neither so now i can remove the lower leaves 

let the leaves yellow then remove

Do as Flitwick says and then pick from the bottom leaving the baby buttons at the top to grow. The heads can be cut as cabbage!!!