discord_delete_messages.js

async function clearMessages() {
	const server = ""; // server id number
	const author = ""; // user id number

	const authToken = ""; // authToken - look inside a network packet
	const headers = { 'Authorization': authToken, 'Content-Type': 'application/json' };
	const baseURL = `https://discordapp.com/api/v6/channels`;
	let searchURL = `https://discordapp.com/api/v6/guilds/${server}/messages/search?author_id=${author}`;
	if (typeof channel !== 'undefined') searchURL = searchURL + `&channel_id=${channel}`;

	let clock = 0;
	let interval = 500;
	function delay(duration) {
		return new Promise((resolve, reject) => {
			setTimeout(() => resolve(), duration);
		});
	}

	const response = await fetch(searchURL, {headers});
	const json = await response.json();
	console.log("There are " + json.total_results + " messages left to delete.");
	await Array.from(json.messages).map(message => {
		message.forEach(async function(item) {
			if(item.hit == true) {
				await delay(clock += interval);
				await fetch(`${baseURL}/${item.channel_id}/messages/${item.id}`, { headers, method: 'DELETE' });
			}
		});
	});

	if (json.total_results > 0) { 
		delay(clock += interval).then(() => { clearMessages(); }); 
	} else {
		console.log("Finished deleting messages")
	};
}
clearMessages();