Asus AP140R-E1 - Manual (Page 110)

6-18 Chapter 6: Driver installation
3. When prompted, press to delete the RAID set or press to
abort the operation.
4. When prompted, use the arrow keys to select either Member#0 or
Member#1 to delete a RAID 1 set member. Select [None] or [Both] if
you want to delete the entire array.
5. To verify if the array was deleted, select Manage Arrays from the main
menu. A No Arrays Present message pops up on the screen if no
array is detected.