See if there are any screws. If there are four screws at the lower four corners, you can remove them by turning them.

If it is an outsourced finished product, it is usually a connector. There is a round fastener about the size of a dime near the joint of the two plates. Screwdriver will loosen when it turns left and right, and some have buttons to buckle.

If it really doesn't work, use functional violence to forcibly remove it, but if the table is damaged, it will not be worth the loss.