By default, the Palo Alto GlobalProtect client automatically starts after logging into your macOS and tries to auto-connect (if configured). This may not always be desirable and there's no real straightforward way to disable auto start from the application itself. Fortunately, as with many auto-start apps on macOS, you can disable auto start through the launch agent files.

Launch agents define what software to start at logon. The global ones (i.e. applicable to all users on a Mac), are located at /Library/LaunchAgents. Although they have the extension .plist, they are in fact XML-files and can be edited with any plain text editor. Note that if you are editing global launch agents, you will   ...

You can very easily properly uninstall the Palo Alto GlobalProtect client on Mac OSX by running the included uninstallation script:

Open a Terminal and then run it by typing:

sudo /Applications/GlobalProtect.app/Contents/Resources/uninstall_gp.sh

Provide your password when asked and the script will uninstall GlobalProtect.