If this is the case, you have two options when you're looking at the ad in question.
You can "Pause" your ad, this will make it disappear from the portal and will not be visible anymore. But it will remain on your profile so that you can easily "unpause" the ad if you ever need to rent it out again.
Or you can "Delete" the ad, it will then be completely removed from the portal and if you need to rent it out again you have to remake your ad.