You can't, at least not if it's a Microsoft Account linked Windows 10 User Account.
It's working exactly as it should and it's expected that if you change your password on your Microsoft Account that will propagate to your machine.
There is, however, a trick you can use if you want a different password on your computer, since a local copy of whatever password you were using is kept, and valid, until or unless you use the new one from your Microsoft Account.
I will pretend that you want to use ABCD1234 as your password on your computer, but not your Microsoft Account.
1. Log in to your Microsoft Account and change the password there to ABCD1234.
2. Log out of your Windows 10 machine, then log in again, using ABCD1234 as your password. This will cause the current locally stored and encrypted password to be replaced by ABCD1234.
3. Log in to your Microsoft Account again and change the password there to whatever you want for it to be.
At this point, you will be able to use ABCD1234 as your login on your machine for as long as you wish so long as you do not use whatever it is you reset your Microsoft Account password to in step 3. If you were to accidentally log in using that password, it will supplant ABCD1234 and become the only valid password, and you'd have to repeat the process again.
I used this technique for a very long time until I started creating portmanteau passwords that I doubt that anyone could crack, but that were easy for me to remember. There was no point in keeping my Win10 login different after that point.
If anyone doubts the above, it's easy enough to test just by changing whatever your Microsoft Account password is that you are also currently using to log in to your Windows 10 linked user account. You'll find that you can continue using whatever the password was immediately prior to the change until you use the newly changed password even once. After that you're back to having the two in sync again.
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