During your trial period, you can quit your job without any problems. In this case you need to inform your employer in writing that you are cancelling your employment contract.
Are you having a part-time employment contract? In that case, it depends on whether a termination clause has been included in your contract. If this is not the case, you are obliged to fulfil the agreed period of time. If you can come to a solution with your employer that you can both agree on, you are free to stray from this rule. But if you do not fulfil the agreed period without any form of agreement, then you are liable to pay compensation as an employee.
Are you employed for an indefinite amount of time? Then you can end the labour relationship after mutual discussion and agreement. As an employee, it is also possible to end your employment contract by yourself. When no proper agreement can be achieved between employee and employer, a cantonal judge also has the authority to disband an employment contract.