Please try to use a search engine for these kind of questions before asking them here or on any other platform.

First of all it is important to know about autocomplete and then you can use a trick to make it impossible for a browser to insert credentials

That's about what you can do if you do not want to enforce JS on your page. Else you could use JS to emulate a password field with a text field and use autocomplete=off on it.

A browser storing a password does not affect security. It is a normal browser control users already know and love. Users can decide by themselves if they want to enable the feature in their browser control and if they want to store the credentials on your site. By crippling regular browser features, you make users angry. It is no good UX.

Browser only offers to save password, it doesn't do automatically, its user who does. Saving password is a privilege not a threat. If user are aware of consequences that saving password might bring, and still they do and something goes wrong unfortunately, then its user who is to blame not browser or a programmer.

Security is a big term the company use to sell their browser, so they actually don't allow much control over their software via javascript.

You may find some dirty hacks around, but that doesn't guarantee that it will work on all browsers or in future versions of the browsers.

Maybe, Maybe not. I don't think it's possible to programmatically disable password managers in web browsers. Even if it were possible it wouldn't change anything much as there are even users that store their passwords on txt files and even on sticky notes. The baseline is that the Client is simply uncontrollable. You just have to do your best from the server side.