You could apply sheet mulching technique to the bed.
Dig out as many of the LOV and DL you want to keep, then cut everything to the ground and scatter the cut greens over the area. Now, if you feel you need to add any amendments, do it now -- compost, manure, etc. -- then water well. Cover the entire area with corrugated cardboard, soak the cardboard, then spread weed-free potting mix or soil mix and mulch.
By laying a 4" layer or more of the soil mix, you can plant shallow-rooted bedding plants here right away. However, it's probably better to let the area mellow for about a week or two first. You'll need to compensate for the cardboard with extra nutrients -- I use compost tea, alfalfa meal tea, fish fertilizer. The earthworms LOVE sheet-mulched beds.
Here's one I built recently: https://www.helpfulgardener.com/forum/viewtopic.php?t=22797&highlight=
This one is a raised bed, involving a bit more digging -- I dug out the path and flipped the grass/sod and topsoil on top before covering with cardboard and 4-layer newsprint paper. I used straw for mulch. I planted the seeds yesterday so I'll update the other thread soon with new photos.
Another option is to solarlize the bed with black plastic and clear plastic sheeting, but that kills everything, so I don't like to do it myself.