Removing types/yfiles to resolve #23310

[yGuy]

• Use a meaningful title for the pull request. Include the name of the package modified.
• Test the change in your own code. (Compile and run.)
• Follow the advice from the readme.
• Avoid common mistakes.
• Run npm run lint package-name (or tsc if no tslint.json is present).

Select one of these and delete the others:

If removing a declaration:

• If a package was never on DefinitelyTyped, you don't need to do anything. (If you wrote a package and provided types, you don't need to register it with us.)
• Delete the package's directory.
• Add it to notNeededPackages.json.

This has been done help resolving #23310.

[typescript-bot]

@yGuy Thank you for submitting this PR!

Because this PR doesn't have any code reveiwers, a DefinitelyTyped maintainer will be reviewing it in the next few days once the Travis CI build passes.

In the meantime, if the build fails or a merge conflict occurs, I'll let you know. Have a nice day!

[typescript-bot]

@yGuy The Travis CI build failed! Please review the logs for more information. Once you've pushed the fixes, the build will automatically re-run. Thanks!

[yGuy]

Huh?! I think I don't understand why the check (all checks) have failed. Actually this looks unrelated to my change, or am I blind?