jira_bulk_delete_inctive.js

function deleteNext() {
    waitAndClick('#inactive-workflows-module-heading h3', () => {
        waitAndClick('[data-operation="delete"]', () => {
            waitAndClick('[name="Delete"]');
        })
    })
    document.querySelector('[data-operation="delete"]').click();
    document.querySelector('[name="Delete"]').click();
}

function waitAndClick(selector, callback) {
    const el = document.querySelector(selector);
    if (el) {
        el.click();
        return (callback) ? callback() : null;
    }
    return setTimeout(() => {
        waitAndClick(selector, callback);
    }, 100);
}
deleteNext();

Above code by https://community.atlassian.com/t5/user/viewprofilepage/user-id/3062032