After 10 years as Westwood’s police chief, William G. Chase last week announced he will retire. Chase will leave the job on Jan. 6 and an interim chief will be appointed while the town conducts a nationwide search for a successor, officials said. Chase will become director of public safety at Fisher College in Boston. Town Administrator Mike Jaillet said it has been an honor to work with someone who has cared so deeply about the safety and well-being of the community and that he is leaving his department well-positioned for the future. Among Chase’s accomplishments were gains in community policing, upgraded infrastructure and training, and community outreach, said Jaillet.