Adding Products To A Category
1. Under Products > Categories
2. Click Categories to go to Product Level
3. At top right, click + Product , top right
4. Either search & select or multiselect by checking boxes
5. Click Save & Close

Removing Products From A Category
1. Under Products > Categories
2. Click Categories to go to Product Level
3. Multiselect or single select products by checking boxes
4. Top right, is the Trash icon top right to initate the delete 

5. Click Yes to confirm deletion.