For your example, it might be something like this:
Goal: Reach 10,000 users (by experimenting with different marketing ideas)
Invert goal: Reduce the number of registered users to zero
Achieve inverted goal: Delete the database, remove the signup buttons, use confusing website copy, suggest better alternatives, remove the most valuable features, make it really easy to delete your account (even by accident), make the site unusable on mobile, block search engines from indexing my website, charge prices customers are unwilling to pay, only accept the least popular payment method
Achieve actual goal: [you can fill this in…]
You are right. Maybe we need more examples to do it properly.
For your example, it might be something like this:
Goal: Reach 10,000 users (by experimenting with different marketing ideas)
Invert goal: Reduce the number of registered users to zero
Achieve inverted goal: Delete the database, remove the signup buttons, use confusing website copy, suggest better alternatives, remove the most valuable features, make it really easy to delete your account (even by accident), make the site unusable on mobile, block search engines from indexing my website, charge prices customers are unwilling to pay, only accept the least popular payment method
Achieve actual goal: [you can fill this in…]