If you want to terminate the rent, you do not have to give your landlord a reason for doing so. However, you do have to take the notice period into account.
If you have concluded a contract for a minimum rental period, for example one year, you are obliged to pay the rent for at least one year. Only after the minimal rental period can you terminate the contract.
In addition, there is often a notice period. If you have to pay the rent every month, then the notice period is one month, even if your rental contract states a longer notice period.
If you do not have to pay the rent every month, it is different. In that case the term of notice may not be longer than three months in any case.
According to the law you must terminate a rental agreement by a registered letter. You then get proof that the letter was sent and received. After the termination you make arrangements with the landlord about how to leave the house or room behind.
A sample letter makes it easier to terminate the rent. You can adapt the text to your own situation. You remain responsible for the letter.
There are many more Dutch sample letters. You can find them all on the website of Juridisch Loket.