You cannot install a "test" version of Play Services over a "production" version if the signatures differ. Stick to the official stable releases on APKMirror to avoid this issue.
: You cannot fully uninstall Google Play Services without root access, but you can "Uninstall updates" in Settings > Apps if a manual install causes issues. exact architecture
What is your (e.g., Samsung Galaxy S8, Moto G6)? Are you currently seeing a specific error message ? Are you using the official software or a custom ROM ?