Danny shouldn't have had to/didn't need apologize to Dash at the end of “Reign Storm.”
Throughout "Reign Storm" Dash and Danny were both having a back and fourth of pranks towards each other which makes sense why Danny was doing it to get back at Dash because Dash was the first one who started it at the beginning of the episode and probably to get back at him for lots of times when Dash bullies him
But at the end Danny had to be the one who apologized to Dash and put an end to it himself for some reason and what does Dash do he puts him on top of the flag pole of their school leaving his underwear out and then accepted his apology after doing that to Danny
Dash didn't take any accountability in the episode for how he was to Danny and never apologized for his own behaviour and never realized that he was at fault as well for starting it and instead Danny had to put an end to it even though he didn't start it and he wasn't even wrong about wanting revenge towards Dash because we all know that Dash never takes any accountability for his actions whenever he bullies people through out basically the entire show