Do I have to uninstall NPM v 10.4 then install NPM v 10.5?
Negative. You just run the installer on top of your existing environment. Here are a few links to help.
SolarWinds Knowledge Base :: Compatibility of SolarWinds Orion Products for Installation and Upgrade
Orion NPM 7.8.5 ⇒ 8.5.1 ⇒ 9.1 ⇒ 9.5.1 ⇒ 10.1.3 ⇒ 10.3 ⇒ 10.6
Installing, Migrating, Upgrading, Licensing (NPM) Knowledge base - SolarWinds