hello, for details how to remove the master password that you've set please refer to Use a Primary Password to protect stored logins and passwords

Are you using Firefox Sync?

• https://support.mozilla.org/kb/what-firefox-sync

Hi cor-el,

I'm just using MOZILLA FIREFOX, is there any solution for stopping the prompt message of asking MASTER PASSWORD except for viewing hidden passwords WITHOUT CHANGING OR REMOVING MASTER PASSWORD.

Firefox will ask for the Master Password on startup if it is needed on a page.
This can be Sync or a web page that is (re)opened automatically and you have saved a name & password for this website.

You didn't confirm whether you are using Sync or not, so I don't know which of the two would apply.