There is no master key.  There is a jumper. Depends on which size you have.

Ship date: August 25, 2013

Country: Czech Republic

210-40058 : OptiPlex 3010 DT : Standard Base Desktop Chassis
619-34199 : Operating System : Windows 7 Professional (64Bit) Czech
620-13430 : MS Media : Windows 7 Professional (64Bit) Resource DVD
340-25960 : Ship Accessory : Czech Docs with European Power Cord
338-BBYY : Processor : Intel Celeron Processor G1610 2.6GHz, 2MB, HD Graphics)
580-17445 : Keyboard : Czech (QWERTZ) Dell KB212-B QuietKey USB Windows 8
570-11142 : Dell USB myš - MS111 - Černá
429-16502 : Optical Drive : 16x DVD-ROM Drive
400-AAMV : 250GB 3.5inch Serial ATA (7,200 Rpm) Hard Drive
370-21916 : Memory : 2GB (1X2GB) 1600 MHz DDR3 Non-ECC
340-31168 : Resource DVD : OptiPlex 3010 Diagnostics and Drivers
340-19745 : Ship Mod : OptiPlex Intel Celeron Label

You remove jumper and clear password.

Then put it back.

You can't use this to remove a hard drive password having moved it from another machine.

The system's software security features include a system password and a setup password. The password jumper disables any password(s) currently in use.
Use the following steps to disable a forgotten password.
1. Follow the procedures in Before Working on Your Computer.
2. Remove the cover.
3. Identify the PSWD jumper on the system board.
4. Remove the PSWD jumper from the system board.
NOTE:
The existing passwords are not disabled (erased) until the computer boots without the jumper.
5. Install the cover.
NOTE:
If you assign a new system and/or setup password with the PSWD jumper installed, the system
disables the new password(s) the next time it boots.
6. Connect the computer to the electrical outlet and power-on the computer.
7. Power-off the computer and disconnect the power cable from the electrical outlet.
8. Remove the cover.
9. Replace the PSWD jumper on the system board.
10. Install the cover.

Deleting or Changing an Existing System and/or Setup Password
Ensure that the Password Status is Unlocked (in the System Setup) before attempting to delete or change the existing System and/or Setup password. You cannot delete or change an existing System or Setup password, if the Password Status is Locked.
To enter the System Setup, press immediately after a power-on or reboot.
1. In the System BIOS
or
System Setup screen, select
System Security and press .
The System Security screen is displayed.
2. In the System Security screen, verify that Password Status is Unlocked
.
3. Select System Password , alter or delete the existing system password and press or .
4. Select Setup Password , alter or delete the existing setup password and press or . NOTE
: If you change the System and/or Setup password, re-enter the new password when promoted. If you delete the System and/or Setup password, confirm the deletion when prompted.
5. Press and a message prompts you to save the changes.
6. Press to save the changes and exit from the System Setup.
The computer reboots

I don't think you understood me. The jumpers are not there nor do I have them and the password is still there.

Removing the jumper DOES NOT CLEAR the password.Ensure that the Password Status is Unlocked (in the System Setup) before attempting to delete or change the existing System and/or Setup password. You cannot delete or change an existing System or Setup password, if the Password Status is Locked.

It allows you to get into F2 CMOS and change that option to unlocked.

Then you clear the password

You then shut down and restart

you put the jumper back

I have this problem too. I was informed that Dell technical dept couldn't do anything for me until this old computer, that was bought 2nd hand, initial owner unknown to me, was  transferred into my name. So, I did this on their system and contacted them again, only to be told it would take 5 to 7 days for that to be entered into their system! So a high tech computer company have systems that don't link to each other and it needs a human to manually update them. I rely on having access to some medical systems that are only accessible to me from that computer, and when I tried to explain that, the technical department simply ended the chat session on me. Not impressed. 

4ttiAQnzqiovQ9B C'est le mot de passe ensuite tu fais un Ctrl + Entrée