For a complete removal of Xcode

Xcode_remove_all_files.MD

For a complete removal of Xcode 10 delete the following:

Run in terminal rm -rf and the lines below one by one

/Applications/Xcode.app
~/Library/Caches/com.apple.dt.Xcode
~/Library/Developer
~/Library/MobileDevice
~/Library/Preferences/com.apple.dt.Xcode.plist
/Library/Preferences/com.apple.dt.Xcode.plist
/System/Library/Receipts/com.apple.pkg.XcodeExtensionSupport.bom
/System/Library/Receipts/com.apple.pkg.XcodeExtensionSupport.plist
/System/Library/Receipts/com.apple.pkg.XcodeSystemResources.bom
/System/Library/Receipts/com.apple.pkg.XcodeSystemResources.plist
/private/var/db/receipts/com.apple.pkg.Xcode.bom

But instead of 11, open up /private/var/in the Finder and search for "Xcode" to see all the 'dna' left behind... and selectively clean that out too. I would post the pathnames but they will include randomized folder names which will not be the same from my Mac to yours.

but if you don't want to lose all of your customizations, consider saving these files or folders before deleting anything:

~/Library/Developer/Xcode/UserData/CodeSnippets
~/Library/Developer/Xcode/UserData/FontAndColorThemes
~/Library/Developer/Xcode/UserData/KeyBindings
~/Library/Developer/Xcode/Templates
~/Library/Preferences/com.apple.dt.Xcode.plist
~/Library/MobileDevice/Provisioning Profiles