Remove, replace, or blur a background

Decide what sits behind your subject: nothing at all, a flat colour, somewhere else entirely, or the same place out of focus.

All of these start by separating your subject from what is behind it, and then differ in what they put back. Four hand the cutout over on transparency, flat white, or flat black. One replaces the scene with somewhere else, one puts the original scene back out of focus for the portrait mode look, and one works inside the photo instead: you paint over something and the model fills the gap with what was probably behind it. The subject itself is left alone throughout, which is why these suit listings, profile pictures, and cleaning up a shot you cannot take again.