Too many UEFI boot entries

Windows 8.1 and Ubuntu 14.04 dual UEFI boot. My notebook only has one disk device. The Grub 2 entries are normal with only Windows and Ubuntu entries. However, when entering BIOS setting, I can see many boot entries, like ATAPI CD0, ATA HDD2, ATA HDD0, ATA HDD1, ATAPI CD1, ATAPI CD2,ATA HDD3... I never used those entries for booting my computer.

I can also confirm those entries by UEFI command like "bcdedit in Windows" and "efibootmgr in Ubuntu".

By bcdedit /enum all > file1.txt:

Firmware Application (101fffff)
-------------------------------
identifier              {280bc1c2-e213-11e3-9d27-ee4f908e4d18}
description             Setup

Firmware Application (101fffff)
-------------------------------
identifier              {280bc1c3-e213-11e3-9d27-ee4f908e4d18}
description             Boot Menu

Firmware Application (101fffff)
-------------------------------
identifier              {280bc1c4-e213-11e3-9d27-ee4f908e4d18}
description             Diagnostic Splash Screen

Firmware Application (101fffff)
-------------------------------
identifier              {280bc1c5-e213-11e3-9d27-ee4f908e4d18}
description             Startup Interrupt Menu

Firmware Application (101fffff)
-------------------------------
identifier              {280bc1c6-e213-11e3-9d27-ee4f908e4d18}
description             ME Configuration Menu

Firmware Application (101fffff)
-------------------------------
identifier              {280bc1c7-e213-11e3-9d27-ee4f908e4d18}
description             Rescue and Recovery

Firmware Application (101fffff)
-------------------------------
identifier              {280bc1c8-e213-11e3-9d27-ee4f908e4d18}
description             USB CD

Firmware Application (101fffff)
-------------------------------
identifier              {280bc1c9-e213-11e3-9d27-ee4f908e4d18}
description             USB FDD

Firmware Application (101fffff)
-------------------------------
identifier              {280bc1ca-e213-11e3-9d27-ee4f908e4d18}
description             ATAPI CD0

Firmware Application (101fffff)
-------------------------------
identifier              {280bc1cb-e213-11e3-9d27-ee4f908e4d18}
description             ATA HDD2

Firmware Application (101fffff)
-------------------------------
identifier              {280bc1cc-e213-11e3-9d27-ee4f908e4d18}
description             ATA HDD0

By sudo efibootmgr > file2.txt:

BootCurrent: 0019
Timeout: 0 seconds
BootOrder: 0019,001B,0006,0007,0008,0009,000A,000B,000C,000D,000E,000F,0010,0011,0012,0013
Boot0000  Setup
Boot0001  Boot Menu
Boot0002  Diagnostic Splash Screen
Boot0003  Startup Interrupt Menu
Boot0004  ME Configuration Menu
Boot0005  Rescue and Recovery
Boot0006* USB CD
Boot0007* USB FDD
Boot0008* ATAPI CD0
Boot0009* ATA HDD2
Boot000A* ATA HDD0
Boot000B* ATA HDD1
Boot000C* USB HDD
Boot000D* PCI LAN
Boot000E* ATAPI CD1
Boot000F* ATAPI CD2
Boot0010  Other CD
Boot0011* ATA HDD3
Boot0012* ATA HDD4
Boot0013  Other HDD
Boot0014* IDER BOOT CDROM
Boot0015* IDER BOOT Floppy
Boot0016* ATA HDD
Boot0017* ATAPI CD:
Boot0018* PCI LAN
Boot0019* ubuntu
Boot001B* Windows Boot Manager

We can see many ATA and ATAPI entries by both commands. But I only need ubuntu and Windows entries.

1. What is the difference between ATA HDD and ATA HDD1?


2. How can I remove them since they are not useful.