Can"t get administrator password so can't upgrade?
i I have bought a secondhand Macbook Pro and so am new to Mac of literally this week. it is currently running on osx 10.8.5 and I want to do the free upgrade to 10.9 mavericks so I can get the apps I need. but to install mavericks it is asking for admin password that the seller did not give me. have tried installing the install disc but no joy. any ideas how I can access the password so I can reset it please? baring in mind I am not very techie in Mac, thanks heaps.