If the opponent uses defog he doesn't remove the screens that he/she put in the field.

[Johann14]

I was playing ranked today, the opponent put Light Screen and Reflect and he used Defog with his Rotom Wash 2 or 3 turns after that, both of screens remained in the field when they should have gone with defog.

[Sin]

Defog only removes opponent’s screens and not your own screens, so that sounds like the move is working properly.

[Johann14]

Yeah, thats right, sorry it was my mistake.