Indexes management is performed using the Indexes/Keys dialog.
To add an index, select Table Designer, Indexes/Keys... from the main menu, and click Add to add a new index. You can then set the index name, index kind, index type, and a set of index columns.
To remove an index, select it in the list box on the left, and click the Delete button.
To change index settings, select the needed index in the list box on the left. The detailed information about the index is displayed in the panel on the right hand side. Change the desired values.