turn on, turn off

Use instead of power on/power off, start/stop, or switch on/switch off to mean turning the device on and off.

Use instead of enable and disable to refer to commands and features that can be activated or deactivated. Or use more specific pairs of words such as make available and make unavailable; show and hide; add and remove; or allow and block. 

Don't use to refer to selecting or clearing checkboxes in instructions. Use select and clear instead. It's OK to use turn on/turn off to refer to webpage options and toggles.

Examples
To turn on pop-up blocking ….
To keep all applied filters, turn on the pass all filters toggle.
If the command prompt isn’t available, your network administrator might have turned off this feature.

See also
Describing interactions with UI
disable, disables (functionality)
enable, enables
shut down, shutdown
unavailable