Don´t do that!!!
But on the contrary you should run the Sideloader update (via InitSetting or KK-Manager) regularly so you gain even more mods by the time.
Why?
So far you´re using character cards from other authors you have to reckon with all these common Sideloader mods the creators usually are using - for example Sykosis
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who is always demanding a fully updated BetterRepack for his amazing creations.
Or do you want to drive a Porsche with an old beetle engine?
The only mods you don´t need are - if you only want to play the game and work with chara maker, but not intensively with StudioNEO , is the [Optional] Sideloader Modpack Studio (alone ~150GB to download). These mods are only usable in StudioNEO and not in game.
If you already have installed it, delete the folder "mods\Sideloader Modpack - Studio".