You can use /* tslint:disable-next-line */ to locally disable tslint. However, as this is a compiler error disabling tslint might not help.
You can always temporarily cast $ to any:
delete ($ as any).summernote.options.keyMap.pc.TAB
which will allow you to access whatever properties you want.
Edit: As of Typescript 2.6, you can now bypass a compiler error/warning for a specific line:
if (false) {
// @ts-ignore: Unreachable code error
console.log("hello");
}
Note that the official docs "recommend you use [this] very sparingly". It is almost always preferable to cast to any instead as that better expresses intent.