If you are trying to cancel an existing registered trademark, or someone is attempting to do this to your trademark, then you will likely be subject to a cancellation proceeding before the USPTO. The party seeking cancellation has the burden of proof and must demonstrate evidence and that they are damaged by the registered mark. It is possible for the TTAB to issues a partial cancellation if it finds that cancellation is only appropriate for a portion of the registered trademark. It is more difficult to cancel a trademark which has been in continuous use for at least five years after registration. Prior to the five-year mark many of the standard arguments can apply such as likelihood of confusion, descriptiveness, genericness, misdescriptiveness, deceptiveness, abandonment, and fraud. After the five-year mark likelihood of confusion and descriptiveness issues cannot be grounds for cancellation. In addition, falsely suggesting a connections or misrepresenting source both can be grounds for cancellation at any time.
This blog is not legal advice and is not specific to your application. You should always consult an attorney.