fetch-sharepoint-post-deleteitem.js

// POST request headers
var postHeaders = new Headers({
    'X-RequestDigest': document.getElementById('__REQUESTDIGEST').value,
    'Accept': 'application/json; odata=verbose',
    'X-HTTP-Method': 'DELETE', // important - ensure DELETE is in all caps
    'If-Match': '*'
});

// POST request options
var postOptions = {
    method: 'POST',
    headers: postHeaders,
    credentials: 'include'
}

fetch(_spPageContextInfo.webAbsoluteUrl + "/_api/lists/getbytitle('Sample List')/Items(1)", postOptions).then(function(response) {
    if (response.ok) {
        // we all good
        console.log('Response was ok!')
    }
    else {
        throw new Error('Network response was not ok.');
    }
}).catch(function(error) {
    // Error handling code goes here
    console.error(error);
    alert('Error has been logged to the console');
})