Get Rid Of
Get rid of means to remove or destroy something you no longer need or want. It can mean to throw something away in the garbage or to give it to someone else.
Ex: Samantha got rid of her children's clothes that were too small and gave them to her friend, whose children were younger than her own.
Similarly, to be rid of someone or something, you simply avoid or free yourself from that thing. To be rid of something implies that it was annoying, or a nuisance, so you are choosing to stay away from it. This is slightly different than get rid of which means to eliminate it completely.
Ex: Anthony hoped to be rid of cigarettes forever with the help of some new gum with nicotine in it. He knew cigarettes were unhealthy and wanted to quit smoking.
The phrase dispose of is often used to refer to something you want to get rid of entirely by removing, selling, killing, or destroying it.
Ex: The hospital has to dispose of all hazardous waste that could infect or harm someone who comes near it. They keep this waste separate from the general waste like paper and food products.
Disposable is used to describe items that were created to be used for a short time and then thrown away.
Ex: My husband and I have decided to use disposable nappies for our baby. We have to use a new nappy every time, but it's a lot less messy than washing used nappies.