Put the delete button as far from other controls as possible.
For example, on many desktop systems the window controls and menus are at the top of the window. The window controls are typically on the right. That tends to mean that the user keeps the cursor more towards the right, so the most common/safe option is usually on the far right, often at the bottom.
Therefore, on such a system you would probably put the delete button in the bottom left corner. It's the most out of the way place, that requires the user to move the greatest distance to reach and this reduces the chance of it being accidentally clicked.