How can I completely remove all the plants and weeds from the garden?

at one time when I bought a house without any flower beds around the house

I had new carpet installed so I had remnants that i laid out on the ground in the pattern I wanted and the grass and weeds died after a couple of weeks which made them easy to pull up. it worked well for me and I hope for you too.

Take a spray bottle and cover the bottom with salt and fill it up with vinegar. Add a few drops of dish soap and shake. Spray on the weeds. When they die, it's easier to pull them up.

You can put down cardboard and weigh it down with rocks.

Landscaping fabric and mulch.