Take off the handle by removing the screw. Sometimes the screw is covered by a piece of trim (either metal or plastic) with an ‘H’ or ‘C’ on it. Once you remove the handle there should be a ‘packing nut’. Once the nut is removed you can remove the cartridge with the seals on it. The seals can now be replaced. There is often a rubber seal on the bottom that is held on with a brass screw. This screw is notorious for the Phillips head to strip. If this happens it is probably game over. Also, the catridge may not want to come out. There is a tool you can buy for removing it but it doesn’t always work.
Go under the sink there is a nut around the faucet loosen it then the whole thing will come out