how did peter lose his power isnt his power getting other people powers by being near them
shouldnt athur lose his power 1st cuz peter hug him 1st??

Peter copies powers. He doesn't remove them.

sorry ok i mean peter copy his father power and his father's power is to remove people abilites right?
and peter huged the father 1st so shouldnt arthur lose his powers before his able to take peter's?

But he didn't know that his father had a power until it was too late.

Yeah he thought he had died at the point in season 1 when he wasn't sure of his own power. So he had no way of knowing his ability, like neddac mentioned above.

Arthurs ability needs to actively focus on taking the person's powers. It doesn't usually happen by accident, just through contact, else Arthur would have taken Peter and Nathan's powers a long time ago