I'd ask why not leave them in? But if you must get rid of them either dig them out individually or use a selective weedkiller specifically designed for use on lawns. I'd recommend Verdone Extra. It's too late for weed killers now so leave it until the grass is growing strongly in spring

It is a little late to use a lawn weedkiller, but I have just used verdone on two and it is working well on lawns that have just recovered from the dry weather.

Snap Bamboo, we posted at the same time.

As I don´t use weed killers..too many animals in the garden, I just dig them out one by one, but usually leave a few because I think they look lovely.