Minimalism is often misunderstood. You don't have to sell your car, TV and all your furniture, not unless you want to (some people do). Minimalism is very much about function and utility. If you use something everyday and it adds value to your life then you should definitely keep it.
On the other hand, something that lies in a cupboard and rarely ever gets used, or even worse, never gets used is a prime candidate for purging. You should aim to eradicate anything that does not get used frequently or that does not add value to your life.
"Getting rid of something doesn't necessarily mean you have to throw it away."
Getting rid of something doesn't necessarily mean you have to throw it away. Instead there are a number of options available to you. You can sell the item and claim back some of the financial cost of acquiring the item in the first place. You could trade the item for one of similar value. You could donate the item to charity. And lastly you could recycle the item. It doesn't have to end up in landfill.
"having one load of laundry instead of many saves water and electricity which is good for the environment"
One way in which I practise minimalism is that I wear a black tshirt, black underwear and black socks, everyday - seven days a week. Yes for those who like bright colours this may seem boring but having one load of laundry instead of many saves water and electricity which is good for the environment. I never have to worry about what to wear either. And a bonus is that by not having to separate my laundry into different colours I save a lot of time as well!
I'd like to leave you with some parting thoughts by noted architect John Pawson. "John Pawson maintains that minimalism is not merely a case of "throwing out the sofa and painting the walls white." This is not architecture of absence, it is defined not by what is not there, but rather by the rightness of what is. You reduce, you simplify and at first there is less and less to look at. Then, as you go on attenuating and compressing, you come to a point at which you go through a barrier and pass through into... a kind of mirror world in which you see, looked at with enough clarity, not emptiness but a sense of richness."
"The minimum could be defined as the perfection that an artifact achieves when it is no longer possible to improve it by subtraction. This is the quality that an object has when every component, every detail, and every junction has been reduced or condensed to the essentials. It is the result of the omission of the inessentials."