Run this script on https://www.linkedin.com/mynetwork/invite-connect/connections/ to remove all your connections. You may need to run it more than once.

remove-all-linkedin-connections.js

(($) => {
  'use strict';

  const click = button => new Promise(resolve => {
    $(button).click(resolve).trigger('click');
  });

  const sleep = timeout => new Promise(resolve => setTimeout(resolve, timeout));

  const process = async () => {
    const dotButtons = $('.dropdown-trigger.mn-connection-card__dropdown-trigger.ember-view');
    if (dotButtons.length) {
      await dotButtons.toArray().reduce(
        (promise, button) => promise.then(async () => {
          await click(button);
          const removeConnectionButton = $('.display-flex.align-items-center.t-14.t-black--light.t-normal')[0];
          await click(removeConnectionButton);
          const removeButton = $('.mv2.artdeco-button.artdeco-button--2.artdeco-button--primary.ember-view')[0];
          await click(removeButton);
          await sleep(500);
        }),
        Promise.resolve(),
      );
      await sleep(2000);
      await process();
    }
  };

  process();
})(jQuery);