Trouble understanding the path factor of Right Effort

The path factor *Right Effort* in the noble eight-fold path contains 4 steps which are ; 1. Prevent the unwholesome that has not yet arisen in oneself. 2. Let go of the unwholesome that has arisen in oneself. 3. Bring up the wholesome that has not yet arisen in oneself. 4. Maintain the wholesome that has arisen in oneself. I understand 1, 3 and 4 but have trouble understanding no 2 - *"Let go of unwholesome that has arisen in oneself"*. Is that done by using the noting-technique and then observing and noting the phenomena until it disappears? Or is it that when e.g. anger has arisen and other techniques dont work then one uses Metta meditation as an anti-dote? Thank you for your time. Lanka