You have to dig/rake them out. Which weed killer did you use some keep working for months?

Which weedkiller you applied is critical - you may need to wait for the weeds to shrivel up and disappear before removing any debris left behind - removed too soon, the roots might still be functioning.

Have used Weedol 2 seema to have worked well but its a new build house and i want to turf in september so i still have to dig them out? Many thanks for all your help...not much of a gardener...yet :o)

To be on the safe side, I'd certainly remove weeds such as dandelions, docks, brambles, but you can do that when you prepare the area for turfing.

The active ingredient in Weedol 2 is not systemic, so perennial weeds will come back from the roots.