Following tries do not work:
/* tslint:disable:"no-unused-variable" */
/* tslint:disable:'no-unused-variable' */
/* tslint:disable:no-unused-variable */
Maybe Webstorm has other linting mechanisms working in the background? How can I disable them, so that only tslint is active?
EDIT: The desired solution would be to do it at the source code level, without configuring any IDE Settings.
This warning doesn't come from TSLint, so configuring TSLint won't help here. This is WebStorm own inspection error. You can either disable this inspection or suppress it for current statement: hit Alt+Enter on 'isDone', then hit Right and choose the appropriate action from the popup. See https://www.jetbrains.com/help/webstorm/2016.1/suppressing-inspections.html#1