JSFiddle - React, Tailwind, and code Playground

JavaScript

let deleteActivity = (activityId) => 
    fetch("https://connect.garmin.com/activity-service/activity/" + activityId, {
        "credentials": "include",
        "headers": {
            "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:125.0) Gecko/20100101 Firefox/125.0",
            "Accept": "application/json, text/javascript, */*; q=0.01",
            "Accept-Language": "en-US,en;q=0.5",
            "NK": "NT",
            "X-app-ver": "5.0.2.0",
            "X-lang": "en-US",
            "X-HTTP-Method-Override": "DELETE",
            "DI-Backend": "connectapi.garmin.com",
            "Authorization": "Bearer " + JSON.parse(localStorage["token"]).access_token,
            "X-Requested-With": "XMLHttpRequest",
            "Sec-Fetch-Dest": "empty",
            "Sec-Fetch-Mode": "cors",
            "Sec-Fetch-Site": "same-origin"
        },
        "referrer": "https://connect.garmin.com/modern/activities",
        "method": "POST",
        "mode": "cors"
    });

fetch("https://connect.garmin.com/activitylist-service/activities/search/activities", {
    "credentials": "include",
    "headers": {
        "Accept": "application/json, text/javascript, */*; q=0.01",
        "Accept-Language": "en-US,en;q=0.5",
        "Sec-Fetch-Dest": "empty",
        "Sec-Fetch-Mode": "no-cors",
        "Sec-Fetch-Site": "same-origin",
        "NK": "NT",
        "X-app-ver": "5.0.2.0",
        "X-lang": "en-US",
        "DI-Backend": "connectapi.garmin.com",
        "Authorization": "Bearer " + JSON.parse(localStorage["token"]).access_token,
        "X-Requested-With": "XMLHttpRequest",
        "Pragma": "no-cache",
        "Cache-Control": "no-cache"
    },
    "referrer": "https://connect.garmin.com/modern/activities",
    "method": "GET",
    "mode": "cors"
})
    .then(res => res.json())
    .then(data => {
    		for (let d of data) {
            if (!d.startTimeLocal.startsWith("2024")) {
                deleteActivity(d.activityId)
            }
        }
    });