Log into your administration area.
Click "Your listing" in the top menu inside the grey bar
Click "Calendar and More" to the right of your listing's picture
Click the 3 lines icon inside the grey bar to the left of your listing's title
Click "Photos" in the menu
Mouse over the photo you want to remove and you will see a little trash can appear in the upper right corner
Click the trash can
Click delete again.
To add more pictures scroll to the very last picture in the gallery and you will see a link to upload.
As a suggestion, turn your phone sideways so more of the room shows. It will also look better when displayed on the AB&B website.
Another suggestion is to remove phone numbers and website addresses from your listing descriptions. AB&B will not show them anyway.