From your clone:
npx datapenny uninstall
That deletes the Worker, so the dashboard, the tracking script and payment webhooks stop working at once. Your data stays in the D1 database.
To keep a copy elsewhere, export it first, from apps/worker:
npx wrangler d1 export datapenny --remote --output=datapenny.sql
To delete your data too, which can’t be undone:
npx wrangler d1 delete datapenny
Then remove the script tag from your sites, and the webhooks from your payment providers.