You did not reply to the questions from bjm_ above. If you can tell us exactly what you are trying to remove, we can offer more help.
Are you trying to remove the extensions from your browsers, or do you want to remove the vault from Norton’s cloud servers?
To remove the contents from the cloud vault you need to try to log into the vault. But after logging into your Norton Account, you need to enter an incorrect vault password three times. After the third time, you will see a link to reset the vault. Resetting the vault erases everything stored and offers to set up a new vault. You just ignore that and move to the next step.
To remove the NPM extensions from your browser, go to the browser’s extensions management pages. Look for NPM and delete it. You will need to do this for all browsers that you installed the extension, and on all computers you installed on.
As for NPM showing up in the new Norton 360 interface, it will still be there but should say Set Up. All you can do about that is ignore it.