If you wish to delete your user account:
You can send a direct message, with your user email, to the Activations Team as described here:
How to request:
You can submit a request of one of these actions to be done using the Support Portal.
Go to the Prismic Support Portal .
Once you’ve logged in or signed up, you can select “Account & Repository Plan Requests”.
Next, select the between the options to request an update to your User Account, Feature Activation / Repository changes, or repository plan.
Last, fill out the appropriate form and click the “Send” button to send us your request. We’ll work to get back to you as quickly as we are able.
If you wish to delete your repo:
You can permanently delete your Prismic repository from your repo's Settings / Danger Zone page.
If you're no longer using your repository, but wish to keep your repository in case you need it in the future, you can instead downgrade it to a "Personal" plan (free) from the Settings / Plans & Billing page.
Note that only the repository owner can do either of these things. If you aren't the owner, then you will need to have the owner do this or transfer ownership over to you.
In order to downgrade to a free plan, the owner will also need to remove all other users from the repository. They can do so from the Settings / Users page. They will also need to remove any pending memberships as well.