If you leave and don't appear in court, then a warrant will be issued for your arrest. This will mean that the next time you try to enter the USA, you will be refused. And, if by some chance you are not refused, then you may be arrested by law enforcement and held for trial.
However, California authorities will not try to have you extradited from Mexico, so if you don't plan to return to the USA, then you can leave.
The only other alternative is to hire a lawyer and try to get the charges dismissed before your court appearance date.
Hope this helps.
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