Is there any way to move labourers from one town to another? For example from one that produces grain to another that produces iron etc..

well you may be able to shut down all resource production in one province, however its impossible to tell where they'll go

Is there any way to move labourers from one town to another? For example from one that produces grain to another that produces iron etc..

Captain2 has got it right. Just funnel workers nto an area by adjusting factories. That typically is what I do.