How to bypass mac os password?

You can reset your Mac Password using the Mac installer CD/DVD

Resetting a Mac password is easier if you havewith yourself an installer disk for Mac. This process uses the disk to remove your password and set a fresh one.

a. Using the Mac OSX installer DVD, boot your system, by putting the disk into the Mac drive and holding down the “C” button while booting.

b. Select the "language preferences" and then beneath the “Utilities” menu select “Password Reset” or “Reset Password” (Depends on different versions of Mac OS X)

c. Select the hard disk drive on which your system is installed, then select that 'username' for which you have forgotten the password. You will then be asked to create a new password.

d. Reboot normally from the hard disk drive, use your newly set password as the login and Done!

Hope it helps you out.