Can Angled Shot detach an equipment from a Ruin Runner?

No, you cannot use Angle Shot to detach an equipment from an opponent's Ruin Runner.

Ruin Runner has the ability: "I can't be chosen by enemy spells and abilities."

Because Angle Shot is a spell that requires you to choose a unit as a target, it is blocked by Ruin Runner's protection ability. According to Rule 352.14.a (referenced in similar rulings for cards like Falling Star and Bellows Breath), if a card specifies that you must choose a unit, that unit is considered "targeted." Since Ruin Runner cannot be chosen by enemy spells, you cannot select it as the target for Angle Shot.