Recommended method of deleting customer data on cloned testing site

Hi, we’ve recently cloned a live/production site to a different domain/DB for testing. It will not be used to push changes to the live site, it’s standalone and strictly for update testing so we needed an exact copy of the live site setup. The shop has a mix of straight physical products (paid via PP or Stripe) and subscriptions (only paid via Stripe).

The test site settings have been adjusted – WP emails switched off (and automated emails logged), access restricted to logged in users and specific IPs, both payment gateways set to test mode, subscriptions in auto staging mode, scheduled actions switched off and site in maintenance mode for good measure. (Hence no URL included here, it’s not a publicly-accessible site.)

What’s the recommended way of removing customer data and/or deleting all existing orders/subscriptions/customers on the testing site (800-odd orders)?

Our only issue here is having an unnecessary copy of customer data (GDPR etc.) on the testing site. Probably a stupid worry but I’m concerned about possible links (via PP?) to the live site, even though it’s on a different domain – I’ve seen at least one person in forums say that when they deleted testing site orders (via a plugin) they were also deleted from the live site.

Would WP’s built-in ‘Remove Personal Data’ be sufficient, and is there any chance of anything going wrong with the live site, whichever way we go about this?

Thanks.