I am not able to kill these weeds in my garden.
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It looks like you have clover and thyme and grass all co existing in the same area. This mix is actually recommended for a low maintenance area.
I do not recommend Round up to solve this. You would have to apply it over the whole area and really soak it in then you would not be able to do replanting for at least a week or more.
It is just as effective to dig up the area with a turf spade and re sod. You would be doing that anyway if you apply Roundup. Or, if you wait till fall you can over seed with grass.
If that is thyme in the photos then the question is how can it compete with grass? Normally grass has no problems out growing it. Thyme thrives on dry soils with lots of sun. Consider applying compost or other organic matter to help retain moisture. This will prevent the thyme from reappearing from any seeds.
I second the recommendation on living with the clover. It will be a chore to get rid of, and really, it's attractive in its own way.
The other weed you have there isn't thyme. Without a closeup it's hard to tell exactly, but I'm pretty certain it's common lespedeza (Lespedeza striata aka Kummerowia striata). This is something you probably want to get rid of, since it's an annual and hence will leave bare spots in the winter. If you take care to pull/mow/weed wack it before it goes to seed, and overseed it once this fall, eventually it will be much less of a problem. Also, if you start mowing relatively high, this will shade the young lespedeza plants and will tend to prevent it from re-establishing itself from its seedbank.