Look, I just did:

    sudo apt-get install qemu qemu-kvm virt-manager

To install it, then when I wanted to uninstall it I ran:

    sudo apt-get purge qemu qemu-kvm virt-manager
    sudo apt-get autoremove

And it seemed to work however after restarting my machine I found that the qemu-kvm.service was still active at startup:

● qemu-kvm.service - LSB: QEMU KVM module loading script
   Loaded: loaded (/etc/init.d/qemu-kvm; bad; vendor preset: enabled)
   Active: failed (Result: exit-code) since Sun 2016-08-14 13:19:28 BST; 33min ago
     Docs: man:systemd-sysv-generator(8)
  Process: 2099 ExecStart=/etc/init.d/qemu-kvm start (code=exited, status=5)

Aug 14 13:19:28 <Computer-Name> systemd[1]: Starting LSB: QEMU KVM module loading script...
Aug 14 13:19:28 <Computer-Name> systemd[1]: qemu-kvm.service: Control process exited, code=exited status=5
Aug 14 13:19:28 <Computer-Name> systemd[1]: Failed to start LSB: QEMU KVM module loading script.
Aug 14 13:19:28 <Computer-Name> systemd[1]: qemu-kvm.service: Unit entered failed state.
Aug 14 13:19:28 <Computer-Name> systemd[1]: qemu-kvm.service: Failed with result 'exit-code'.

Aug 14 13:19:23 <Computer-Name> ureadahead[866]: ureadahead:/lib/udev/rules.d/60-qemu-system-common.rules: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-alpha: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/lib/x86_64-linux-gnu/qemu/block-curl.so: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-arm: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/lib/x86_64-linux-gnu/qemu/block-iscsi.so: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/lib/x86_64-linux-gnu/qemu/block-dmg.so: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/lib/x86_64-linux-gnu/qemu/block-rbd.so: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-aarch64: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-cris: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-i386: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-lm32: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-m68k: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-microblaze: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-microblazeel: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-x86_64: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-ppc64: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-ppcemb: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-sh4: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-sh4eb: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-sparc: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-sparc64: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-unicore32: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-xtensaeb: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-mips: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-mips64el: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-mipsel: No such file or directory
Aug 14 13:19:24 >Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-or32: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-ppc: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-xtensa: No such file or directory
Aug 14 13:19:24 <Computer-Name> ureadahead[866]: ureadahead:/usr/bin/qemu-system-mips64: No such file or directory
Aug 14 13:19:25 <Computer-Name> systemd[1]: qemu-kvm.service: Control process exited, code=exited status=5
Aug 14 13:19:25 <Computer-Name> systemd[1]: qemu-kvm.service: Unit entered failed state.
Aug 14 13:19:25 <Computer-Name> systemd[1]: qemu-kvm.service: Failed with result 'exit-code'.
Aug 14 13:19:25 <Computer-Name> ureadahead[866]: ureadahead:/usr/share/qemu/init/qemu-kvm-init: No such file or directory
Aug 14 13:19:27 <Computer-Name> systemd[1]: qemu-kvm.service: Control process exited, code=exited status=5