Even though the value of the Studio/Cognitive City is that your data is being stored in a graph and not a table, it's sometimes helpful to just look at it as a simple table. The data view allows you to see an element type as a table, and from this table, delete elements, change the values of individual elements, or manually create new ones.
To access this view you can open the "Data" menu in the left sidebar (screenshot below on the left), or hover over any element type in the model builder and click the "View" (screenshot below on the right.)
Both methods will take you to the table-based view of the data associated with the selected element type:
From this view you can:
1. Edit elements by double clicking on a blank spot of any row to launch the data-entry form for that element.
2. Delete elements by selecting or multi-selecting and then clicking the "Delete" button that appears at the top of the table.
3. Create a new element of that type by clicking the "Create" button in the upper right corner of the page.
More advanced curation, like merging element together, can be done using the in-network curation features.