How do I make my land bigger

I would like to make the land grid my house is on bigger, I cannot place a larger grid onto the site but I can place several 10x10 plots around my land grid. Is there any way of making my land bigger apart from world editor ( my understanding of world editor is you make your own towns etc, not edit the Sims town you are already in. Is that correct?) Can I merge the 10x10 plots with my land grid? I have tried buying them but I cannot remove rubbish bin or postbox. Any input would be appreciated.