Less is more when it comes to pruning a Damson Plum.
All pruning should be done while the tree is dormant; early Spring or late Winter.
Shape the tree and prune away any dead or diseased material.
Remove any suckers as soon as they appear.
Most gardeners want the tree to have one central leader.
Once the tree reaches the desired height you can cut off the trunk just above the top branch. Maintain this height by pruning the top and tallest branches each year.