Python script that bulk delete all DNS records. Since CF does not provide an api to delete all records, this script can do the same easily. CF_ZONE_ID and CF_AUTH_ID are two environment variables required for this script.

script.py

import requests
import json
import os

zone_id = os.environ['CF_ZONE_ID']
token='Bearer '+ os.environ['CF_AUTH_TOKEN']
authentication={'Authorization' : token}

list_url="https://api.cloudflare.com/client/v4/zones/{0}/dns_records".format(zone_id)
delete_url="https://api.cloudflare.com/client/v4/zones/{0}/dns_records/{1}"

## get no of pages from request list_url using request module
response=requests.get(list_url,headers=authentication)
no_of_page=response.json()['result_info']['total_pages']

## loop through all pages and delete all records
for i in range(1,no_of_page+1):
    response=requests.get(list_url,headers=authentication)
    result=response.json()['result']

    for j in result:
        delete_uri=delete_url.format(zone_id,j['id'])
        print(delete_uri)

        response=requests.delete(delete_uri,headers=authentication)
        print(response.json())