The brake lever of Shimano's BL-MT200 is too long for me, can I modified it to a shorter one?

MT200 has what is called Reach Adjustment - which brings the level closer to the handle bars. To do this you need a small hex key (Can't remember i its 2 or 2.5mm).

Also when mounting the brakes you are best to mount them inboard with about 2-3cm from the handgrip. I prefer to have the shifters mounted outboard of the brake lever, but thats personal preference.