How do you remove/update your listings when sold?

Too easy.
But this is for information only and not legal advice.
Go to the agent's website or phone your listing agent, click to download your instant agent delete form or phone if you have a traditional olden tyme agent, fill in the instant agent delete and instant listing delete form and attach to an e-mail back to your agent and have it signed by the Managing Broker of the office.

If you are changing agents or want to list yourself using the new For sale by Owner on the MLS to save thousands, or you think you may have someone you know personally who wants to buy and you don't feel like parting with a 20K commission when you have done all the sales work, then you need to have the clause that gives the listing agent 60 days to collect from your sales efforts struck out so as to make this an instant listing delete or Terminate Listing form.

Make sure to have your agent have the managing broker initial or sign beside the 60 day clause you have struck out.

Some boards use a slightly different form than others, and if you really are going to stay in your home and not sell, then leave in the 60 day clause because "Who cares."

However, if you do sell and you have not struck out the 60 day clause and your agent wants the 20K commission, remember your agent can only collect on the listing side or 10K. (Assuming a 500K home sale price at traditional commission rates)
The other half of the commission or BUY SIDE 10K is yours, as you acted as your own agent for the buyer, which anyone can do as you do not need a real estate license to buy and sell real estate. There is a law of common agency.

But to get on the MLS we do need that license.

The new FSBO on the MLS rules are about to make license exempt agents a lot more popular, but that's another answer for another question.