Ubuntu – Remove network interface permanently

I'm trying to remove a network interface permanently. For some reason, ifconfig lists eth0 and eth1, although the latter RX/TX metrics remain at zero.

I suspect that extra eth1 entry might be causing delays during boot.

Surprinsgly, a search did not yield any answer on how to proceed. Most posts either are for older versions of Ubuntu or Debian, or for other distros (RedHat), or have no permanent effect, or pertain to adding an interface, or try to turn it off but after it's been started, or are simply unanswered. But the answer might be somewhere after Google's thrid result page.

Removing the second entry from the desktop (up and down arrows, on the top bar) has no effect either on ifconfig.

EDIT: I actutally do have two network cards on the MB. That's a bit of a surprise I admit. I don't have wifi. Question still stands, a least out of curiosity.

krakoukass@durum:~$ ifconfig
eth0      Link encap:Ethernet  HWaddr 00:1f:d0:a3:40:d9  
          inet addr:192.168.1.66  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::21f:d0ff:fea3:40d9/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:84 errors:0 dropped:0 overruns:0 frame:0
          TX packets:93 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:12255 (12.2 KB)  TX bytes:12241 (12.2 KB)

eth1      Link encap:Ethernet  HWaddr 00:1f:d0:a3:40:db  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:634 errors:0 dropped:0 overruns:0 frame:0
          TX packets:634 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:64758 (64.7 KB)  TX bytes:64758 (64.7 KB)

krakoukass@durum:~$ lspci | grep -i eth
04:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 02)
05:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 02)

krakoukass@durum:~$ cat /etc/network/interfaces
# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback

krakoukas@durum:~$ systemctl -l status ifup@eth1.service
● ifup@eth1.service - ifup for eth1
   Loaded: loaded (/lib/systemd/system/ifup@.service; static; vendor preset: enabled)
   Active: active (exited) since Fri 2015-05-15 12:36:34 CEST; 14min ago
  Process: 457 ExecStart=/bin/sh -ec ifup --allow=hotplug %I; ifup --allow=auto %I;      if ifquery %I >/dev/null; then ifquery --state %I >/dev/null; fi (code=exited, status=0/SUCCESS)
 Main PID: 457 (code=exited, status=0/SUCCESS)

May 15 12:36:34 durum systemd[1]: Started ifup for eth1.
May 15 12:36:34 durum systemd[1]: Starting ifup for eth1...
May 15 12:36:34 durum sh[457]: Unknown interface eth1

krakoukas@durum:~$ systemctl -l status ifup@eth0.service
● ifup@eth0.service - ifup for eth0
   Loaded: loaded (/lib/systemd/system/ifup@.service; static; vendor preset: enabled)
   Active: active (exited) since Fri 2015-05-15 12:36:34 CEST; 15min ago
  Process: 458 ExecStart=/bin/sh -ec ifup --allow=hotplug %I; ifup --allow=auto %I;      if ifquery %I >/dev/null; then ifquery --state %I >/dev/null; fi (code=exited, status=0/SUCCESS)
 Main PID: 458 (code=exited, status=0/SUCCESS)

May 15 12:36:34 durum systemd[1]: Started ifup for eth0.
May 15 12:36:34 durum systemd[1]: Starting ifup for eth0...
May 15 12:36:34 durum sh[458]: Unknown interface eth0

Thanks in advance for you help.