Ah, gotcha. I'm a poor person to ask, then, because I don't agree that the classes are that imbalanced in 5E...I haven't noticed any problems with balance at my table, anyway. EDIT: That's not entirely true. There was a problem with a certain Sorcerer/Warlock character, but the balance issues were caused by feats and multiclassing, not from the default rules of the game. I don't believe that wizards should be less powerful than fighters, either, but only because it doesn't really fit the vibe I'm going for in my campaign. (My wife, on the other hand, is looking for a low-magic game system to play for their next campaign, because 5E D&D is basically All Magic, All the TimeTM and it's nigh impossible to dial it back. They're looking into the Witcher RPG at the moment.)
Sorry, got off track.
But for the sake of discussion? If I did think that wizards were too powerful, I'd go the super-easy route and add this to my house-rules: "The wizard class has been removed from this campaign. If you were interested in playing a wizardly character, ask me about other options." And then if someone had any heartburn with it, I'd chat with them, find out what they were hoping to get out of the wizard, and meet them in the middle. If it was just certain cantrips or the 6th+ level spells, I could add those to the Artificer spell list. If they were just hoping for a Necromancer with the Arcane Recovery feature, I could replace the cleric's Channel Divinity ability with it. And so on.
But I'd bet dollars to donuts that nobody at my table would care. If I got any response at all from my friends, it would be something like "No wizards? Weird. Oh well, I'll play a sorcerer instead."