US Tax - I'm not US please

In the time I was receiving the email to submit the w30 form, I couldn’t submit it, now it reduces an amount for tax but I’m not a US person, can any body please tell me how to get rid of it, It cuts a lot in my little earning, Please help

You can’t get rid of it, that tax is not for “US person” it’s because you are selling to customers in US. Every sale you make in the US is subject to their withholding tax.

Most countries in the world have withholding tax on payments to foreign persons, so does the USA!
You (foreign person) have income at a US company (Envato USA Inc. handles all sales to US customers) and this income is taxed.

Sri Lanka has a double-taxation treaty of 10% with the USA.
Submit the W-8 form with your taxpayer identification number (the ID you use to pay taxes in Sri Lanka) and you only pay this 10% on US sales.