Remove Reward Store Rewards?

You can also do this with cheats if you don't want or can't use this mod. 

You need to type 

traits.remove_trait [trait_codename]

The codename is the name of the trait.

So for example if you want to remove the markatable trait you have to type in the cheat

traits.remove_trait trait_Marketable

A more detailed explanation and a list of the traits can be found here 

List of Traits in The Sims 4 | EA Forums - 4937330 

The rewards traits are listed here

List of Traits in The Sims 4 | EA Forums - 4937330

Edit: I am not quite sure if the second link works as intended. If you follow the first link, go to Non-Pack Filtered Visible Traits en then to Reward Store traits you should find the list.

All credit for this list goes to EgonVM . No point in typing it all out again if this simmer already provided such a complete an helpful overview.