What happened if I reset one course. It will remove my xp earn from that course?

Answer 1

yes.

Answer 2

Sarthak Dandgawhal

Reset course means your progress is 0 so if progress is 0 then XP is 0

Answer 3

If you reset any course then you will all you XP associated with that course, the challenges you played in that language will also become 0.

You XP got deducted and if you check leaderboard then you may find that your XP is negative number on that day/week!