You should pull up and remove weeds by hand as and when they appear. If it is a regular problem, you might need to reseal the paving. In extreme cases, the sub layer itself may need to be re-laid. You can use weed killer, however some paving can be discoloured by stronger weed killers.
Dulas
Dulas or City Dulas is a village in Anglesey, in north-west Wales. It is positioned on the A5025 roadway, near the shore (Dulas Bay) at just 5 metres (16 ft) over sea level. The village has never ever held the condition of a city and also "City" is not a recognisable Welsh word, so its beginning is vague. It may be that the name came from an Anglicisation of Saith Ty, which is Welsh for "7 Houses". There are two places in Wales simply called 'City': City, Powys and City, Vale of Glamorgan.