After you've opened the table you want to modify in Design view, click the field selector (the leftmost column of the table) for the field you want to delete. A right-facing arrow appears.
The field is selected. Click the Delete Rows button on the Standard toolbar in the main Access window.
The field is deleted. Click the Save button on the Standard toolbar in the main Access window to save the changes to your table.
If your database includes fields that you do not need, you can delete them. Keep in mind, though, that if you have already entered data into the table, you will lose all the entries in the field you deleted.