How to I kill my grass so I may plant clover instead?

Probably the best way would to be cover it with layers of newspaper or card board, or even the plastic weed barrier to prevent sunlight from reaching the grass. No sunlight, no photosynthesis, no grass. It will take time to do this and it doesn't look pretty, but perhaps you can put down wood mulch and potted plants to make it look better while you are waiting. If you put down cardboard or newspaper, you will have to renew it as is breaks down so that no sunlight reaches through. Do not use vinegar, it will sterilize the soil and nothing will grow until the soil is amended. There are chemicals you can use, but check the labels, some of them do have very short wait periods, just make sure it isn't one of the ones safe for grass.

My backyard lawn was a mess so I replaced it last spring. I used vinegar to kill the existing grass and weeds. Took 2 applications. Then my gardener used a sod cutter to dig out the old dead grass and weeds. Then the area was tilled and amended and we spread seed. I used marathon fescue grass (you don't want that) and white clover. LOVE the clover. Soft and fluffy underfoot, doesn't need mowing if you don't want to, drought tolerant and adds nutrients back into the soil. I have pets and won't use chemicals. Especially Round Up which contains glyphosate, which is surrounded by controversy and I am following the lawsuit trail.

White Clover may need to be reseeded each year until firmly established. Otherwise, it's great!