If you have Bluetooth devices — such as keyboards, mice, or trackpads — paired with your Mac, and you plan to keep these devices, you can unpair them. This optional step prevents accidental input on the Mac if the computer and the Bluetooth devices have separate owners but remain within Bluetooth range of one another.
If you're unpairing an iMac, Mac mini, or Mac Pro, you must have a USB or other wired keyboard and mouse to complete these steps.
To unpair your Bluetooth devices, choose Apple menu > System Preferences, then click Bluetooth.
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Hover the pointer over the device that you want to unpair, then click the remove (x) button next to the device's name.
When the dialog asks if you're sure, click Remove.
If you're using an iMac, Mac Pro, or Mac mini, use a USB or other wired keyboard and mouse to complete the next step.