Hello @Allan94,
I've never used a MAC so can't say if the the Airbnb site layout appears differently on them to on a Windows machine.
If your listings page doesn't show some settings or menu button for the listing you want to delete then one option is to go through the process to complete the listing and then select to permanently deactivate it. If you do this, make sure to set the nightly price very high so no one will book it in the few minutes it takes you to deactivate it.
Deactivating a listing on a Windows machine is done by going to your listings, selecting the one you want to remove and scrolling down to the end of the page. Then in the "Listing status" section click on "Edit". Then click the "Permanently deactivate listing" link.
You could also contact Airbnb support.
Type "contact airbnb" in the "Search the community" box on these forum pages where you posted your question. Scroll down a little in the list of suggestions that appears and click on the "Contact Airbnb: A Community Help Guide[UPDATED]" one. That lists phone numbers and ways to contact them via Twitter or Facebook.
Steve.