Chairs can be deleted, not tables tho, but if you look closer, you can see the foot of the table right under the display case, I placed it over the table, not instead of the table, although I think, they can change the ID number of the table, and it would turn into something else.
Some highlighted things, can be removed, some not, everything Drakoni put on our bank right now are highlighted, just because he didnt lock it yet.
The only no-removable things I delete for my design were the trees, because I considered it is worth it to modify the map for this, lets face it, the trees right now are not making us any favour.