Currently, Pokémon GO has not build-in option to delete your account. So you won’t find such option the settings menu for example.

But luckily it is possible to fully delete your Pokémon GO account and erase all data associated with it. Pokémon GO is operated by Niantic Inc. and they have a support team which can remove your account. To get in touch with them, use this link.

Remember that:

• I understand that a profile deletion request is IRREVERSIBLE, and attempts to cancel the request after submitting can’t be guaranteed.
• I understand that after submitting this form, my Pokémon GO profile and all associated game data will be permanently deleted.
• I understand I will not be able to reuse this email once my profile is deleted.
• I understand I will not be able to reuse this nickname once my profile is deleted.

So think twice before submitting your request!