Make link like this

    <a href="http://example.com/?reaction=smk_remove_post&id=1226&_nonce=7be82cd4a0" data-id="1226" data-nonce="7be82cd4a0" class="smk-remove-post">Remove post</a>

And jQuery

    $('.smk-remove-post').on( 'click', function( event ){
        event.preventDefault();
        var _this = $(this);
        
        var data = {
			'action': 'smk_remove_post_ajax',
            'reaction': 'smk_remove_post',
			'id': _this.data('id'),
            '_nonce': _this.data('nonce')
		};

        // since 2.8 ajaxurl is always defined in the admin header and points to admin-ajax.php
        jQuery.ajax({
            type: "GET",
            url: ajaxurl,
            data: data,
            success: function(response){
                console.log(response);
                _this.text('All great, the post is removed.');
            }
        });
    });

See Codex about [AJAX in Plugins](https://codex.wordpress.org/AJAX_in_Plugins).
And in Codex, it says:

> Most of the time you should be using wp_die() in your Ajax callback function. This provides better integration with WordPress and makes it easier to test your code.

So use `wp_die();` instead of `die();`