Right-click and then choose "Delete". On a Mac holding the mouse button or left mouse button a second then release might serve as a right-click, but I can't imagine anyone having but a single button anymore on a Mac. My mouse has 5 buttons on the top not counting left/right horizontal scroll.

You can use Control-click to do a right-click.

All I have ever had is a single button mouse. This is the stock mouse. Am using an imac and cordless mouse and cordless keyboard. The mouse is one big button. I cannot conceive of a mouse with five buttons.