how do you remove garlic smell from a marinade

Don't add garlic

I think if you want garlic flavor in your end product, which will mellow when it cooks, the aroma of the marinade is part of the process.

Some acid, like lemon juice, will also tone down excessive garlic flavor, but as for the smell in a marinade, I'd keep your container sealed as best you can and/or cut your marinating time down.

If the marinade is too garlicky (perhaps the garlic was old? or too much was added?) you could add a little extra of the other ingredients, especially something neutral like oil. If it is yogurt-based, add a little extra of that. You might add a little extra salt which seems to smooth overly-bold flavors. In any event, cooking the item being marinated may tone down the garlic taste.