If your question is to stop the default behaviour of any password being saved by the browser then go to your Okta admin console, select "Settings" and then "Customization". Then down the left hand side of the page find the section "Browser Plugin", select "Edit" and then set the value of "Block browsers from saving passwords for Okta apps" & "Block browsers from saving passwords for Okta apps " to Yes, and set the value of "Enable Okta toolbar for group " to the group "Everyone" and then save.
If its the way that you dont want users to save the passwords to Okta then ask your user's to select the option "Disable for all apps" from the example image below:
Jumping on the thread to see if I can answer lingering questions.
1. Okta no longer has any option under Customize->Browser Plugin as this was a feature that was not truly working appropriately, it was removed as a default option from tenants. To disable browsers from saving user passwords you'd have to manage this setting through the browser itself.
2. Currently the Plugin has a feature that allows it to create a chiclet once an end user visits a website (the screen shot that Kevin attached in his comment), to disable this the end user can select "Disable for all apps" or if you want to disable this altogether, you can contact Okta support and have the feature disabled from the back end, just ask to have the "App on the fly" feature disabled.
It's important to make a clear distinction between the two above points, #1 is a Browser built in feature that will try to save credentials and #2 is a feature in Okta that we do have control over. If you want to gain more insight into the above or you have further questions, please raise a ticket with support and we will be more than happy to help out!