If you are going to a community college or tech/trade school, you do NOT need to take the SAT/ACT.
If you are going directly to 4 year college/university, you may need to take the SAT/ACT.
UCs and CSUs no longer consider SAT/ACT test scores in their admissions decisions.
If you are applying to private universities or out-of-state colleges, check with each school to see if they are accepting scores. If they are "test-optional", it is up to you whether you would like to take the SAT/ACT. It is encouraged, however, that you take the test and submit your scores. Schools like to see that you've challenged yourself. Also, if your scores are better than average, it may positively influence your admissions decision.