Can Repulsor Blast’s first point of damage remove a tough status card from an enemy, then its additional damage deal…

No. The additional damage that Repulsor Blast deals is a simultaneous modification of its first point of damage. For instance, if a player were to discard 2 energy resources due to Repulsor Blast, they would deal a total of 5 damage to an enemy all at once, as the additional 4 damage dealt by the discard effect happens at the same time as the first point of damage.