The reason there are candidates on your ballot who have dropped out of the race is due to state law requirements. In Washington, the primary roster had to be finalized by early January to allow for the printing and mailing of ballots.
State law mandates that each major political party must provide its final list of candidates to the Secretary of State's Office no later than January 9 in order to ensure the delivery of ballots and Voters' Pamphlets to military and overseas voters. Each political party is responsible for deciding which candidates are printed on their side of the ballot. Once the list of candidates is submitted to the Secretary of State, changes cannot be made.
https://www.sos.wa.gov/elections/voters/helpful-information/presidential-primary-faq