Hello, I’m Nathan, and I’ll be assisting you today. My livelihood depends on your positive feedback, so your satisfaction is my highest priority.
Sorry to hear you’re having trouble.
There are 2 halves to this bracket, the wall side and the monitor side. The 2 halves have an interlocking tapered (dovetail) joint, wide at the top, narrower at the bottom. Grab the monitor on both sides and lift, straight up (not forward, not tilted), and the 2 halves will lift apart. The wall bracket portion will be attached with screws/bolts that are easily removed with a drill/driver.
Note: If it won't lift up (feels stuck) then there may be a security screw in place.
on the bottom are 2 tabs that can accommodate a standard philips screw for added security. To remove that, you'd have to take a screwdriver straight up behind the monitor to unscrew, and the it will lift off.
Here is an image of what it looks like, so you can see where the screws would go: