Delete all users on a WordPress site who haven't logged in for one year

query.sql

-- Step 1: Delete from wp_usermeta
DELETE FROM wp_usermeta
WHERE user_id IN (
    SELECT ID 
    FROM wp_users
    WHERE ID IN (
        SELECT user_id
        FROM wp_usermeta
        WHERE meta_key = 'last_login'
        AND FROM_UNIXTIME(meta_value) < DATE_SUB(NOW(), INTERVAL 1 YEAR)
    )
);

-- Step 2: Delete from wp_users
DELETE FROM wp_users
WHERE ID IN (
    SELECT user_id
    FROM wp_usermeta
    WHERE meta_key = 'last_login'
    AND FROM_UNIXTIME(meta_value) < DATE_SUB(NOW(), INTERVAL 1 YEAR)
);

First try it on a staging site dont directly use on production. You can run this MySQL query from your PHPMyadmin area in your database management on the hosting. This should remove the ones who haven't logged in for a year via the INTERVAL 1 YEAR Command in the query yiu can adjust it according to your requirement.