How is a decision tree pruned?

Question

Can somebody explain what pruning is?

Answer 1

Pruning takes place when branches with a weak predictive power are removed from the model. This eventually increases the accuracy of the decision tree and helps enhance the model by reducing the complexity and avoid overfitting of the model. 

Here is an explained application of pruning :

https://intellipaat.com/community/26202/can-anyone-tell-me-in-simple-ways-about-cost-complexity-in-decision-tree-with-examples