To get to Lv. 10 on any job, use the CASE-SENSITIVE boolProp Testingcheatsenabled true cheat in your lot, sign up for the job you want at any level, and shift-click on the newspaper and select job level 10
This is a good cheat to boost your grade performance quite easily. You need to have quite a bit of influence and you must not have done you term paper yet. Firstly, you should influence another Sim write your term paper, they'll head to a computer and start writing it, make sure no-one interrupts/talks to them.
Once they are nearly finished, go to another computer and write your term paper aswell, the other Sim will still keep writing it. Once you are finished, 2 infomation bubbles will come up to the side, one saying that so-and-so have finished your paper for you and one saying you have finished you paper. Check you grade performance bar and you'll notice that there is double the work filled in than if you had written alone.
If you wan't to have all the freedom of being a young adult, without the hassle of university all you have to do is:
While you are in your chosen university bring up the cheat window (Ctrl+Shift+C) and type in "aging off", this will not stop the term bar progressing, but when you graduate and move back to the regular neighbourhood your sims will not grow up. For the disbelieving amongst you this is true you can do literally anything!