How do I remove and replace deck mount basins?

You loosen and disconnect all of the plumbing underneath the basin but be sure to turn off the water first. Remove the taps first and then use a sharp knife to loosen the compound around the basin rim so that it lets go from the top of your cabinet. Then replace the basin with a special caulk just under the rim of the basin, line up the plumbing and install your faucet. You will need a new outlet plug in the basin so this is the time to change it out before connecting to the waste line. This is a good time also to upgrade your faucets. You may need a new P trap too. It is best to have all parts available before you start and if you do not need them return them, providing you keep your sales slip.

I don't know what a deck basin is

Hi Eva! Fortunately there are many great videos to help you with this.

https://www.wikihow.com/Replace-a-Bathroom-Sink

https://www.youtube.com/watch?v=tgoMwoEpCsU