1. Look in Actions - [05] Spindash. There are 2 headings in a row, "Events" and "Roll if the player isn't holding down anymore". Find where it says to set Action in Player_MovementValues to 6, and replace 6 with 0.
2. Go into Actions - [00] Common. Scroll down, and there's a header "Rolling", followed by 2 events. Delete them. Done.