lessen
verb [ I or T ]
uk/ˈlesən/ usto make something smaller, less noticeable, etc., or to become smaller, less noticeable, etc.:
Corporate executives are keen to embrace "green technology" in order to lessen their dependence on fossil fuels.
Increasing security procedures is the only way to lessen the risks of air travel.
lessen the impact/importance/influence (of sth) Experts argue that a carbon tax would lessen the influence of special-interest groups in the climate change debate.