Coming from the older ebizmarts Mailchimp extension? Moving over is a single step, and there is nothing to uninstall.
The easy way: migrate from the admin
If your previous extension has a saved API key and you haven’t connected an account yet, the Setup Wizard’s first step shows a Migrate from ebizmarts Mailchimp button. One click copies your key and settings, then switches the old extension off. Its code and data stay in place, so you can switch back if you ever need to.
Prefer the command line? Run:
bin/magento mailchimp:migrate:from-mc-magento2 --dry-run # preview, no changes
bin/magento mailchimp:migrate:from-mc-magento2 # migrateThe command copies your settings. To finish, open the Setup Wizard and complete the connection there; your account then appears on the Connected Accounts page.
Both extensions can be installed side by side
No need to uninstall anything or rush the switch. While the previous extension is switched on for a store view, the new one simply waits; a notice in your admin tells you so.

To hand over a store view: open Stores → Configuration → Mailchimp → General (the previous extension’s own settings) and set Enabled to No for that store view. Refresh the page and the notice is gone; the new extension takes over from there.

When you complete Go Live in the Setup Wizard, the extension takes care of this switch for the store view you are connecting. If the notice still shows, flip the setting as above and refresh.
Prefer the command line? bin/magento module:disable Ebizmarts_MailChimp also works, and uninstalling is never required.
You are disabling Ebizmarts_MailChimp — the classic extension, with a capital C in MailChimp. Do not disable Ebizmarts_MailchimpMarketing: that is this extension, and turning it off stops your sync.
Your orders, customers and products re-sync from scratch so Mailchimp matches your current catalog exactly. Existing contacts already in Mailchimp aren’t touched. The re-sync never changes anyone’s subscription status. Contacts you unsubscribed stay unsubscribed.
If the previous extension’s Campaign Attribution setting was active, you may notice your Mailchimp revenue attribution shift after migrating: it returns to Mailchimp’s own native model, the same behavior as Mailchimp’s other ecommerce integrations. This is expected and correct, and it needs no action; there is nothing to disconnect or reconnect.
The extension registers its own webhook with Mailchimp automatically. Nothing to change on the Mailchimp side.
Questions along the way? Troubleshooting has the answers, and ebizmarts support is one email away.