"Unnecessarily replacing a task that does not exist is not supported" - Error

I get this error when trying to run the code that is further below.

Unnecessarily replacing a task that does not exist is not supported. Use create() or register() >directly instead. You attempted to replace a task named 'PDFCreator.main()', but there is no existing >task with that name."

Everything that comes up in the console/terminal when trying to run it (I run it by using the small green arrow and not by using "start gradlew.bat run", as i have another main method which is run that way, if it matters at all):

23:51:25: Executing task 'PDFCreator.main()'...


FAILURE: Build failed with an exception.

* Where:
Initialization script 'C:\Users\myusername\AppData\Local\Temp\PDFCreator_main__.gradle' line: 18

* What went wrong:
A problem occurred configuring root project 'blablabla'.
> Could not create task ':PDFCreator.main()'.
   > Unnecessarily replacing a task that does not exist is not supported.  Use create() or register() directly instead.  You attempted to replace a task named 'PDFCreator.main()', but there is no existing task with that name.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

Deprecated Gradle features were used in this build, making it incompatible with Gradle 7.0.
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/6.0/userguide/command_line_interface.html#sec:command_line_warnings

BUILD FAILED in 956ms
23:51:26: Task execution finished 'PDFCreator.main()'.

The code I am trying to run:

package blablabla;

import com.itextpdf.io.image.ImageDataFactory;
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfWriter;
import com.itextpdf.layout.Document;
import com.itextpdf.layout.element.Image;
import com.itextpdf.layout.element.Paragraph;

import java.io.FileNotFoundException;
import java.net.MalformedURLException;


public class PDFCreator {

    public void createPDF2() throws FileNotFoundException, MalformedURLException {
        PdfDocument pdf = new PdfDocument(new PdfWriter("Test.pdf"));
        Document document = new Document(pdf);
        Image img = new Image(ImageDataFactory.create("https://images.unsplash.com/photo-1542044896530-05d85be9b11a?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=1000&q=60"));
        document.add(img);
        document.add(new Paragraph("Dette er en test"));
        document.close();

    }

    public static void main(String[] args) throws FileNotFoundException, MalformedURLException {
        PDFCreator klient = new PDFCreator();
        System.out.println("Hei");
        klient.createPDF2();
    }
}

I have tried to google around a bit but haven't found any solutions that work. I have tried:

1. Deleting .IDEA folder
2. Deleting .gradle folder
3. Restarting IntelliJ several times
4. Clearing IntelliJ cache
5. Restarting computer
6. Git pull lots of times (The code works on my friend's computer)
7. Deleting the file where the error occurs (Under the *Where: in the message from the terminal)

As I do not know what to try next, I am hoping that someone here can help me :) In advance, thank you for your help :)

SOLUTION: In IntelliJ settings - gradle - change build and run to IntelliJ and not Gradle.