SAT VS ACT?

I originally planned only to take the SAT but my teachers are now telling me to take the ACT. I really don’t want to since they said ACT is mostly for privates and I only plan on applying to UC’s. I know UC’s don’t require ACT scores and I’m a bad standardize test taker so should I take the ACT though?

If I take the ACT and get a bad score, will colleges see it? Or can I pretend like I never took the ACT lol…

As far as I know, all colleges want you to send in either ACT scores or SAT scores. This includes the UCs.
Take a practice test for both in normal test conditions and see which one you like better. The ACT is going to include more of the recent material that you probably learned; but, the time constraints are harsher imo.

Edit: Also there will be a new SAT starting March 2016. The old SAT is only available until January 2016. That is probably why your teachers recommended that you switch to the ACT.

You can pick what you want to send to colleges - SAT, or ACT, or even both. Colleges will not know what you took, or what score you got, unless you send the scores to them. The tests are somewhat different - you might do better on the ACT and it might be worth taking. Taking a few practice tests for both SAT and ACT is a good idea. If you do relatively better on the ACT practice test, it would be worth taking the actual test.