Can I delete Garage Band without impacting other functions??

Yes, you can. The steps are same as deleting any other apps. Tap & hold on the app icon, select remove app, choose delete app, tap delete.

Deleting it won't affect any other functionalities, but deleting it will delete its data as well. So make sure to backup any projects before deleting the app.

r u sure it won't corrupt the mainframe and cause a meltdown?