Question
who i can rid of white powder in my soil. it is eating the roots of my plants and it
is rotating the stamp and killing all my plants. please i need the solution.

Answer
Hi Ishrat, Most soil fungi is beneficial.  I'm not certain the white powder is actually causing you harm.  You may have an unseen root rot fungi, but that's hard to diagnose without looking at an affected plant.  I'd take one of your "dying plants", a soil sample and a sample of the "white powder" to your local garden center for a correct identification.
Should you need to spray a soil fungicide, I like Agri-Fos.  It controls a wide range of soil fungal problems and it is not terribly expensive.
But before you spray, have an expert look at your plant.  It may need some adjustment in care practices as well as a fungicide.  Jim