You can purchase sulfur from a local chemist. You can also go on Amazon and look for sulfur powder from chemists online.

See the FAQ referenced below to learn how to burn sulfur and incense.

When you burn sulfur, use only a pinch; it is a very strong and toxic substance. Leave the room, and do not leave any living things in it, such as pets. I would also recommend moving any plants if you have any while you're cleaning.

Remember also to air out the room once you are done. You can burn sulfur for nine consecutive days and, wallah! you have a wonderfully cleaned home. It is also recommended that you also burn some aromatic incense afterward in order to mask the smell from the sulfur.