Hello first.
My question is, how can i use clutch (just to test it) on a non clutch wheel i have the logitech nascar wheel. do I have to press the clutch on every gear or what??? might sound quiet noob xD

If you want to disable autoclutch then yes, on all cars except the BF1, you must use the clutch for every gear, both up and down. Rev matching is possible but I wouldn't recommend it as it works rather strangely and, at least for upshifts, is very slow.

On downshifts without the clutch with autoclutch disabled you simply have to: preselect the lower gear, let off the throttle (the transmission will then pop out of gear into neutral), and then bring the revs back up, at which point the lower gear will engage automatically. With that said, I still don't think this is any faster than using the clutch to downshift, and in fact is probably slower. There is also the danger that the gear does not catch when you bring the revs back up, forcing you to either wait for the revs to come back down or clutch it.

I've tested it a little and i see that when i press the Up gear button and then lift up the acelerator the gear change by itself... that makes me slow right?

Yes, that's known as rev matching and it is MUCH slower than using the clutch due to having to wait for the revs to fall before the gear is engaged.

Cool, i have to see if i get use to it if not i'd have to turn it back on

how do you remove the clutch if you press it by accident

Remove the bind under the Control options.