How do I turn off controller aiming in Zelda: BotW?

The setting you are looking for is called "Motion Controls", which can be enabled/disabled via the games settings.

For Breath of the Wild, as seen on this guide, motion controls can be turned off by disabling "Aim with motion controls".

Breath of the Wild Settings

Skyrim has a similar setting. While I could not find a screenshot, you can follow the Q/A on Bethesda Support

Yes, the motion controls are on by default. They can be disabled/enabled via Journal -> Settings -> Gameplay. There are two separate toggle options: Enable Motion Control and Enable Gesture Attacks.