Under Preferences > Locations you can make DerivedData relative to each project and I recommend you do that so different apps you work on don’t force you to wip

Under Preferences > Locations you can make DerivedData relative to each project and I recommend you do that so different apps you work on don’t force you to wipe all the artifacts from all apps when you clean it manually. As for removing old simulators after you remove an old Xcode, run $ xcrun simctl delete unavailable