To delete a distribution list:
On the Home tab, select Addresses and then Address Lists. The Address Lists Editor window appears.
Under All Books and Lists, select Distribution Lists.
Under Contents of 'Distribution Lists,’ select a distribution list.
Tip: To select multiple lists, hold down the Shift key.
Click the Remove button. A confirmation message appears.
Click the Yes button to delete the selected distribution list or the No button to cancel the deletion.
Tip: If you selected multiple lists in step 3, confirm/decline the deletion of each distribution list by clicking the Yes or No button or else confirm/decline the deletion of all selected distribution lists by clicking the Yes All or No All button.
When you are finished, click the Close button.