To remove administrator restrictions on a Windows PC, first open Local Security Policy, which is under Administrative Tools. Go to the left side of the Local Security Policy window, click Local Policies, and open the Security Options folder. On the right side of the window, right-click User Account Control: Run All Administrators in Admin Approval Mode, select Properties, select Disabled, and then click OK. On your next restart, the administrator restrictions previously on your account should be disabled.
You can bypass a password-protected administrator account using Ubuntu. If you don't already have Ubuntu installed in the computer, create a boot-disk, and boot into it using the Try Ubuntu option. Once inside Ubuntu, search "Chntpw" in the Synaptic Package Manager window. Click the result under that name, and install the package.
Mount the drive with the windows installation, navigate to the Config folder, open Terminal, type "cd /media/", and hit Enter. Next, type a command in the format "sudo chntpw -u ACCOUNTNAME SAM", where ACCOUNTNAME is the name of the administrator account you wish to bypass, and hit Enter. Wait a few seconds, press 1, hit Enter, and press Y when asked to confirm your action. Close the program, and reboot into your Windows operating system. The administrator account should no longer have a password.