Clearing Potion Effects

So i was making a boss who rides a horse and when hes riding the horse he gets stronger by giving him strength. but my problem is i want the potion effects to disappear when the horse dies and idk if there is a command that will some how get rid of potion effects if anyone has any way to some what recreate it or can help me i would appreciate it i have tried
command{c="effect <mob.uuid> clear"} @trigger ~onInteract but it didnt seem to work