You can disable XCTests run by Xcode by right clicking on the test symbol in the editor tray on the left.
You’ll get this menu, and you can select the “Disable ” option.
Right clicking again will allow you to re-enable. Also, as stated in user @sethf’s answer, you’ll see entries for currently disabled tests in your .xcscheme file.
As a final note, I’d recommend against disabling a test and committing the disabling code in your xcscheme. Tests are meant to fail, not be silenced because they’re inconvenient.