Magnetic lasso tool on Macpro

New user here! I have PS Elements in a MacBook Pro 13. When using the magnetic lasso tool, if I make a mistake (like going a bit overboard so that he border doesn’t snap to the desired edge), how can I correct that without deleting the entire section? Manual instructions says you should press the Delete key to erase points along the border, but Mac Pro doesn't have that button =/. Heard that pressing fn+ backspace should work, but I get Siri instead. Pressing only backspace also doesn't work. Please help!!!