You've gotten a lot of really bad advice here. You will need to review your country's tax treaty with Thailand to determine if that rental income is taxable in Thailand, your home country, or both.
The tax treaty likely specifically addresses income from rental property in your home country, and will state which country can tax it. It's possible that the income is not taxable in Thailand. There is no way to know without reading the tax treaty.
In my case, I have a business in my home country, and my country's tax treaty states that business income is only taxable in my home country even though I live in Thailand. I remember reading about income from rental property in the tax treaty, but can't remember how it was treated.