Drying marks are generally on the back of the neg, which is relatively hard, and can be gently removed using a microfibre cloth over one finger, dabbed in clean tapwater. Before it dries again (which takes only seconds), dry it gently with a dry bit of the cloth. Old linen handkerchieves used to be recommended in the 1960s, but microfibre cloths are much better (yes, I am that old).

I read somewhere in the Ilford technical stuff recently that drying marks are more likely if you don't use a stop bath. I don't know why this would be, but recently I stopped using a stop (if you see what I mean), and drying marks have appeared in my life again.