Have you tried typing msconfig rum then press ok. click on Boot and tick safe boot. If you also want an internet connection tick network as well.Apply ok. Then it will start in safe mode. You may have to reverse those settings when you want to get back into windows normally.
That the easy way to do it so i suppose you have already tried that.
Now of course we have to ask is it your computer or are you allowed to use it.
Only the the owner of the computer can change things on the computer others will not have permission to change anything .