I was thinking about a way to get rid of the aileron, and I was wondering if:
I install two motors on the wing, and make the right one spin faster than the left one, will my wing roll to the left ?
First thing first: I think you mean yaw not roll. See Yaw definition
If you actually mean roll, then the answer is no.
If you mean yaw; then the answer is yes. However it is impractical for two reasons:
1) Engines, especially jets but also propellers have a latency when speeding up and down. This will make it impractical, and might create pilote induced oscillations. Electrics motors are more reactive, but so far they have yet to be commonly used in aviation.
2) Redundancy. If one engine fail.... you have to shut down the second engine, and you lost yaw control.
It will not primarily affect roll but it will affect yaw. And if your wing have any yaw-roll coupling (and swept wings certainly do) the yaw will cause your wing to roll a bit but generally not much and generally not completely controllable by you.
Here' one flying wing with no moving control surfaces:
Note that without elevons you're limiting yourself to basically flying level so no snap turns or rolls or even more fancy stunts.