After you've opened the table you want to modify in Design view, click in the Field Name column for the field you want to change.
Select the field's current name, and then type over the selection with the new field name.
The field's name is changed. Click the Save button on the Standard toolbar in the main Access window to save the changes to the table.
Each field has a unique name that identifies it. Because these names are used in other Access objects, such as forms and reports, it's wise to use descriptive, yet succinct, names when possible. If you do not like the name you assigned a field, or if a default name assigned by the Table Wizard doesn't suit your needs, you can easily change a field's name.
Renaming a Field in Datasheet View
You can also rename a field in Datasheet view. To do so, right-click the field's column and select Rename Column from the list that appears. Type a new name and then click outside the field name.