You can add or delete rows or columns in a table by using the commands in the Rows & Columns group on the ribbon. (The Rows & Columns group is on the Table Tools Layout tab, which appears when you click in the table.)
You can also add or delete a table row or column by clicking the row or column, right-clicking, and then clicking an Insert or Delete command on the shortcut menu.
This video takes a quick look at each option:
For more information about tables in Word, see the following articles:
Word 2010: Add or delete a table
Word 2007: Insert or create a table
Word 2003: Create a table
– Joannie Stangeland