How do I edit the shortcuts on my Charge 3

[greeru]

How do I erase activities I don't use (swimming) and add ones I do

Moderator Edit: Clarified subject

[JohnnyRow]

See How do I track my workouts with my Fitbit device? 

If the exercise choices are all used, you will have to delete one or more to see the other choices.

[greeru]

Thanks...I mean how do I erase something I never do and replace it with a
workout I do. I can’t find a way to erase something and replace it with
say, a spin workout.

Also,activities don’t stay erased....they reappear in the watch.

[JohnnyRow]

Did you follow the link I gave, and look at the section titled "Can I change or reorder the exercises on my Fitbit device?"