Chroma key, alpha channel, materials.

Four types of material are available in the editor: - flat – "plain background"; - standard – applies highlights and shadows to the image; - chroma-key – used to remove a real green or blue background filmed on video; - alpha – for removing a background created in a video editor. Perfectly removes a black background. Allows creating fire effects, preserves neon glow when removing the background, and is applicable for other effects.
The scene with the removed background looks more spectacular.

Background can be removed in images and videos. If an image background is not removed correctly, use an external online resource or editor. For example this one https://www.remove.bg/ru.
For background flat, chroma-key and alpha are available.

The alpha channel has fine adjustment. Use it if the object has artifacts or looks unrealistic after background removal.