Go to https://expo.dev and login. You’ll see a list of projects on the left of the page.
If you don’t see the one you want to delete in that short list, click on the “All projects” link below that list. You might have to go to the correct page using the “<”, “>” buttons on the bottom right.
Click on the project you want to delete. The URL should look like: https://expo.dev/accounts/username/projects/slug-name
Then on the left there will be a menu with “Settings” at the bottom. Click that.
Then in the main part of the page you’ll see some Project Settings. Scroll down to “Danger Zone” and you’ll see an option to delete the project.