It depends on how big the saplings are. If they are this years or lasts then you should be able just to pull them out as the roots will not be deep and break off easily. If larger then use a garden fork.

If quite large--trunks more than an inch in diameter--cut them off, and then immediately paint the cut surface with concentrated SBK, being careful not to spill it on the ground.

Many thanks for the responses - good to know how to deal with those I can't dig up.