Remove test cases by going to a test suite's details and clicking on Subtract (-) from within the Test Case List section.
Go to Tests > Test Suites.
Click on the name of the test suite you would like to subtract test cases from. The test suite's details page appears.
Click on the Subtract (-) button that's at the rightmost column of every test case row.
A toast notification confirms that you've removed the test cases from the test suite. The subtracted test cases also disappear from the Test Case List.