How to drain some oil from car?

1 cm is way, way too much! If you can get the front up reasonably high it's not hard to loosen the drain plug with a wrench and then undo the rest of the way with your hand. Take it right out and let 2 full Litres go into the drain pan and then simply put the plug back in quickly. If you do it properly it can be done surprisingly easily. If you don't have the room or the skill, just dump it all in a clean drain pan and put back the correct amount.

You will probably find that 1cm over the full mark is at least 2 Litres over full. The level should be between the marks, not at the top. If you check again cold, in the morning after sitting all night you'll know why I say this.

Your oil level should be between low and high on your dipstick. If level above high then you need to remove oil as this can cause problems. A couple of ways, remove oil filter or a syringe with a tube, it does work albeit a slow process. Do not remove drain plug, you may lose a lot more oil than necessary.

The clean way is to get some windscreen washer tubing that you can slip down the dipstick hole, and connect it to the bottom of the pump bit of a trigger spray. Slow, but clean. Will go faster if the engine is warm. Not too hot or you could melt things.

If you do as you say you will lose too much oil. 1 cm is nothing and will do no harm at all. Stop worrying.

unscrew th drain plug a few turns, but not so it comes all the way out/ then some will come out and close it when enough is out

remove the oil filter, and empty it out, then put it back on. will take out at least 1/3 quart