You can make something as simple as a door rotate, as doors do, very easily by moving the axis using the joint editor. This is assuming it is a separate object, which it is likely to be.

Select the joint editor tool and you should see a green and a red widgit in the shape of blobs with arrows sticking out. Move the green one to the edge of the door where the hinge would be using the arrow manipulators. As with a door hinge it will need to be on edge of the narrow side of the door, not in the middle. You can put it on the bottom corner. When you dial Y Rotate (assuming it's an upright door) the door will now rotate from one side, just like a real door.

In the properties editor, if you like, you can rename "Y Rotate" to "Open Door" (right click this property and select Settings/Label). You can also put limits on its rotation here with Settings/Limit.. and lock and/or hide the other rotations if you are tidy minded.

You will need to save the object under Save - Support Asset - Figure/Prop Assets.. to keep these properties.