Thanks!
I think I have found a possible solution. The custom field ‘_event_end_date’ contains the ending date of an event in a MySQL datetime format. I did create a filter to hide all events that ended before the current date as following: http://i.imgur.com/vgHgTf4.png
Basically anything that has ended, is filtered out.
You can even make that filter invisible, by using the custom CSS code, if you want to:
[html]#ajaxsearchprobsettings1_1 form .asp_custom_f:nth-of-type(1) {
height: 0px !important;
opacity: 0;
margin-top: 0 !important;
}[/html]