curl "https://app.tatango.com/api/v2/lists/<ID>/custom_fields" -d '{"key":"some_custom_field_name"}' -X DELETE \
  -H "Accept: application/json" \
  -H "Content-Type: application/json" \
  -u emailaddress@mydomain.com:my_api_key \
  -H "Host: example.org" \
  -H "Cookie: "

require 'net/http'
require 'uri'

uri = URI.parse('https://app.tatango.com/api/v2/lists/<ID>/custom_fields')
http = Net::HTTP.new(uri.host, uri.port)
request = Net::HTTP::Delete.new(uri.request_url)
request.basic_auth("emailaddress@mydomain.com", "my_api_key")
request.body = {"key":"some_custom_field_name"}.to_json
response = http.request(request)

var request = new XMLHttpRequest();
request.open('DELETE', 'https://app.tatango.com/api/v2/lists/<ID>/custom_fields', false);
request.setRequestHeader('Content-Type', 'application/json');
request.setRequestHeader('Authorization', 'Basic ' + btoa('emailaddress@mydomain.com:my_api_key'));
var data = JSON.stringify({ key: 'some_custom_field_name' });
request.send(data);

import requests

url = "https://app.tatango.com/api/v2/lists/{ID}/custom_fields"

payload = { "key": "some_custom_field_name" }
headers = {
    "Authorization": "Basic <encoded-value>",
    "Content-Type": "application/json"
}

response = requests.delete(url, json=payload, headers=headers)

print(response.text)

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://app.tatango.com/api/v2/lists/{ID}/custom_fields",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "DELETE",
  CURLOPT_POSTFIELDS => json_encode([
    'key' => 'some_custom_field_name'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Basic <encoded-value>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://app.tatango.com/api/v2/lists/{ID}/custom_fields"

	payload := strings.NewReader("{\n  \"key\": \"some_custom_field_name\"\n}")

	req, _ := http.NewRequest("DELETE", url, payload)

	req.Header.Add("Authorization", "Basic <encoded-value>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.delete("https://app.tatango.com/api/v2/lists/{ID}/custom_fields")
  .header("Authorization", "Basic <encoded-value>")
  .header("Content-Type", "application/json")
  .body("{\n  \"key\": \"some_custom_field_name\"\n}")
  .asString();

{
  "status": "Custom field successfully deleted"
}