NOTE: Please note that Gen1 devices have a slightly different locking mechanism than the one shown in this article. See the corresponding images in the Quick Start Guides for each device which can be found in the Downloads page.
The round UniFi Access points have a locking feature to ensure a secure (and anti-theft) hold to the wall mount. In order to release an AP, simply slide a flat, thin object (zip ties are the Community favorite) into the locking notch of the AP (opposite of the cable feed hole) and twist counterclockwise. The zip tie (or similar) just needs to be firm enough to lift the latch less than a millimeter and allow the AP to twist.
Other objects that have worked for community members are small flat-headed screwdrivers, a thick twist-tie, toothpicks, hairpins, among others.