Open Finder > Applications > Utilities > Terminal.

If you want to install an even older build then you can try this approach to remove iTunes: Note these builds are not compatible with macOS 10.14 Mojave. See Deploy apps in a business environment with iTunes - Apple Support for more on these builds. ITunes isn't particularly easy to remove from OS X but it should be possible to install the 12.6.5.3 build over any later version, and then install the build you require as long as it has a higher build number. iTunes12.6.5.3.dmg () Last build to support app management in iTunes.iTunes12.8.1.3.dmg () Final build for OS X 10.10 Yosemite.iTunes12.8.2.3.dmg () Final build for OS X 10.11 El Capitan - macOS 10.12 Sierra.iTunes12.8.3.1.dmg () Current build for macOS 10.13 High Sierra.You can reinstall Mojave to repair iTunes. Updates to iTunes are included in OS updates when applicable.

There is no standalone installer provided. Note: macOS 10.14 Mojave includes iTunes 12.9.x as part of the operating system. Here are some links to older builds of iTunes direct from Apple's secure servers in case you are running an older version of macOS and want to try reinstalling the current build, or try working with an older version when the current build doesn't work properly for you for some reason: See What happened to iTunes? - Apple Support for details. ITunes was replaced in macOS 10.15 Catalina and subsequent releases of macOS.

For iphone instal iTunes 12.12.10