The data is now again in the state from before your change. Here are some steps on how to most easily make the change you want:
1. To adjust the shapes, drag the points of each existing shape to where they need to be. To merge to points, simply drag one onto another.
2. Once that's done, you can select multiple buildings by holding the shift key and clicking on them. Then hit the "Q" key, that makes all the angles 90 degrees.
(Many of the buildings in this area don't have 90 degree angles because they come from an import of government data with "imperfect" shapes.)
3. Now select the building that your business is in and add the business data as you did. It's also good to add the website and phone number if the business has these.

As a general hint, hitting the "W" key changes the the display mode of the objects, making it easier to see details in the imagery.

Hope this helps and let me know if you have any questions!

Happy mapping,
Paul