Ok, managed to trash the table too. I moved the house to a far corner and a table leg was finally grab-able:
Only problem is, the lot is now on a 64x64, not 20x15. Maybe you could repro this but on a smaller lot? Not sure how well it would work though. Definitely worth a try!
Edit - no problem with it being on a bigger lot, thanks to @CGrant56 for pointing that out below 🙂
Following up on what @Bluebellflora said, if you do move the lot to a larger lot to delete the table and chair, you can move it back to it's original location on the smaller lot. All you have to do is use the "Place Lot and Edit" option rather than the "Place Lot" option. The button for that is right next to the "Place Lot" button when you go to place it from your Library. You should be able to place the entire lot since it was built on the smaller lot. The key is as long as the main house fits on the lot, it will place. You might lose the fence and some landscaping but the house should be there at least but in your case, if you try to place it on the same size lot on which it was built, you should be able to save it all.
Edit: Btw, you can do this from either Map view or you can go to build from live mode with sims on the lot. The difference it that in live mode, you just use the "Place Lot" option. The "Place Lot and Edit" button isn't there. From map view, you have to use the "Place Lot and Edit" option.
Hope this helps.
