I know in the Apple Health app > Workouts > Show All Data you can find incorrect workouts and delete them. In Workouts you used to be able to Add Data Point which included distance, type start/stop and calories, but I don’t know if that’s still possible (I’ve removed 3rd party apps that write that data and don’t own an Apple Watch, so I have no data saved of that kind now)
EDIT: Someone figured out how to hack their rings with this (you apparently can add calories but you can’t change your Steps).