Why are they here? How do I get rid of them and keep this from happening. Very annoyed
Hi!
Fake customers are go through registration form.
The most popular solution to avoid it is enable recapcha by Google in the Shopify admin panel.
Shopify documentation about recaptcha: https://shopify.dev/themes/trust-security/captcha
If you have some 3th party app for managing forms, you can add hidden field to form for filtering robots. The details of hidden field depends on the app settings.
But how do I quickly delete the 90,000 bad customers without having to go through 2000 pages individually?
You might help customers segment functionality: https://help.shopify.com/en/manual/customers/customer-segmentation/customer-segments/customer-segments-managing
Or using some Shopify extension (3th party app): https://matrixify.app/tutorials/bulk-delete-customers-shopify/ (just for example)