Reset Nintendo DS games?

I found a couple of old Nintendo DS games that I would very much like to sell. However, I want to reset the game status beforehand so that all data is deleted and the buyer can enjoy the game from the beginning. However, I don't know how to reset the score on these games.

A list of games follows here:

Hello Kitty Big City Dreams

Tinkerbell

Cars 2

Kim Possible Kimmunicator

Littlest Pet Shop

Kim Possible Chasing Gemini

All of the above games are games for the Nintendo DS. I hope you could help me

I'm happy about every reply

Do you still have the instructions? There should actually be a key combination that you probably have to hold down when entering the game to get to an EraseAll screen. It may even be the same for all ds games.

especially since the games up there are all quite below average, right?

Or you use Google, at least that would have been my suggestion.

I don't even know any of these games.